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  • Correction to: Field-Orientation-Dependent Dynamic Strain Induced Anisotropic Magnetoelectric Responses in Bi-layered Ferrite/Piezoelectric Composites
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-07
    Jitao Zhang, Kang Li, Dongyu Chen, D. A. Filippov, Qingfang Zhang, Shuaiyong Li, Xiao Peng, Jie Wu, Roshan Timilsina, Lingzhi Cao, Gopalan Srinivasan

    In the original version of the article, Roshan Timilsina’s first and last names were transposed. It is correct as reflected here. The original article has been updated.

    更新日期:2020-01-04
  • Recent Research Trends in Point Defects in Copper Iodide Semiconductors
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-27
    Satoshi Koyasu, Masahiro Miyauchi

    Copper iodide is a transparent p-type semiconductor that can be applied in thin-film transistors, transparent conductors, and light-emitting devices. Point defects affect the semiconductor properties of copper iodide. Therefore, many researchers have attempted to reveal the properties of point defects in copper iodide. A typical optical property related to point defects is photoluminescence (PL). PL peaks (430 nm and 700 nm) derived from defects have been reported for single-crystalline copper iodide. Density functional theory (DFT) studies reveal that the most stable defect species is the copper vacancy (VCu). These studies report that PL energies and defect species can be associated using experimental and DFT analyses. Researchers have also introduced defects into copper iodide single crystals or thin films artificially by controlling the annealing atmosphere and observed the relationship between the PL or absorption energy and Cu/I ratio. A comparison of this result with DFT results revealed that the photoactive defects were copper vacancies (VCu), iodine vacancies (VI), and iodine ions substituted at copper sites (ICu). Elucidation of the origin of fluorescence and coloration has enabled active control of optical properties via synthesis conditions. However, more drastic control of optical or electrical properties by doping is required for fabrication of actual devices. Some DFT studies on chalcogen doping have been reported; however, more theoretical and experimental studies are required.

    更新日期:2020-01-04
  • Magnetic Dodecahedral CoC-Decorated Reduced Graphene Oxide as Excellent Electromagnetic Wave Absorber
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-27
    Hongfang Qiu, Xiaoyu Zhu, Ping Chen, Sen Yang, Xiang Guo, Jialiang Liu, Xiuling Zhu

    Abstract A two-step method has been adopted to synthesize cobalt nanoclusters in carbon (CoC)-decorated reduced graphene oxide (rGO) from graphene oxide (GO) and ZIF-67 as an excellent stable electromagnetic wave (EMW) absorber. Firstly, the electrostatic force between GO and Co2+ gave rise to in situ growth of ZIF-67 on GO (ZIF-67–GO). Then CoC–rGO was obtained by calcination of ZIF-67–GO hybrids. The ligand is introduced as the nitrogen source to GO. The crystal structure, chemical composition, and magnetic properties of CoC–rGO were investigated by x-ray powder diffraction analysis, Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and vibrating-sample magnetometry. The morphology was observed by scanning electron microscopy and transmission electron microscopy. By adjusting the ratio of GO to ZIF-67, the electromagnetic parameters of CoC–rGO can be optimized. It was found that the sample consisting of 10 wt.% CoC–rGO-2 in a paraffin matrix exhibited excellent EMW absorption performance, reaching a minimum reflection loss (RLmin) of −44.77 dB with thickness of 2.1 mm and an effective bandwidth (RL ≤ −10 dB) of up to 5.2 GHz at thickness of 1.8 mm. The results of this study open an effective and simple avenue for the design of EMW absorbers using metal–organic framework (MOF) and low-cost carbon materials.

    更新日期:2020-01-04
  • A Density Functional Study on the Sensitivity of Small ZnO Nanoclusters to Sulfamethazine Considering Semilocal and Nonlocal Functionals
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-04
    M. Yeganeh, P. S. Maddahi, F. Badieian Baghsiyahi

    Abstract In this study, the possible application of small ZnO nanoclusters in the development of biosensors was investigated by density functional theory. Sulfamethazine is an antibiotic compound with an extensive range of prophylactic and therapeutic applications in animal husbandry. Because of the environmental risks associated with the overconsumption of antibiotics, the development of precise and selective detection methods is imperative. In this regard, the interaction of sulfamethazine and ZnO nanoclusters was investigated utilizing the semilocal functional of Perdew, Burke, and Ernzerhof and nonlocal functional developed by Vydrov and Voorhis. The results showed that the antibiotic can be adsorbed on ZnO nanoclusters. By considering van der Waals interactions, an increase was observed in adsorption energy when compared with the semilocal functional. Inclusion of van der Waals forces, however, did not alter the spatial configuration of the adsorbed molecule. The imaginary part of the dielectric function of ZnO nanoclusters was reduced upon antibiotic adsorption, which became more pronounced in the case of larger ZnO nanoclusters.

    更新日期:2020-01-04
  • Structural, Morphological, and Optomagnetic Properties of La/Cu/Cu-Mn Ferrite Ternary Nanocomposites
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-22
    R. Rajesh Kanna, K. Sakthipandi

    Abstract CuFe2O4 (CF), Cu0.5Mn0.5Fe2O4 (CMF), and Cu0.5Mn0.5Fe1.5La0.5O4 (LCMF) ferrite nanocomposites were synthesized by simple sonochemical reaction. The structural, optical, and magnetic properties of the prepared CF, CMF, and LCMF ferrite nanocomposites were analyzed through x-ray diffraction pattern, Fourier transform infrared spectra, ultraviolet spectra, x-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and vibrating sample magnetometer loop. The crystal size of the LCMF ferrite ternary nanocomposite was less than that of the CF and CMF ferrite nanocomposites. XPS revealed the oxidation state (Cu 2p, Mn 2p, La 3d, Fe 2p, and O 1s) and the binding energy of the element present in the prepared CF, CMF, and LCMF ferrite ternary nanocomposites. The scanning electron microscopy images showed spherical morphology. The optical bandgap energy of LCMF was 5.33 eV higher than that of the CF (1.66 eV) and CMF (2.10 eV) ferrite nanocomposites. The coercivity of the prepared ferrite nanocomposites confirmed soft magnetic nature of the CF, CMF, and LCMF ferrite nanocomposites. By doping a small amount of La3+ ions in CMF nanoferrite, it was found that the doped LCMF ferrite ternary nanocomposite has a high permeability, which enhances the useful magnetic properties of LCMF ferrite nanocomposite for electronic devices. The optical bandgap and high permeability of the LCMF ferrite ternary nanocomposite are more suitable for microwave absorption application.

    更新日期:2020-01-04
  • Experimental Approach to Determine Damage Curves for SnAgCu Solder Under Sequential Cyclic Loads
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-26
    Elviz George, Deng Yun Chen, Michael Osterman, Michael Pecht

    Miner’s rule assumes that damage in solder interconnects accumulates linearly under cyclic loading and is independent of the load sequence. Under these constraints, damage is equivalent to cycle ratio, defined as the ratio of the applied cycles to the cycles to failure for the specific cyclic loading condition. Due to these inherent assumptions, Miner’s rule can inaccurately estimate solder interconnect life under sequential loading conditions. A nonlinear damage model with load-dependent damage exponents would take into account the effect of loading sequence under sequential loading conditions. In the nonlinear damage model, damage is related to cycle ratio using a power law relationship with a load-dependent damage exponent. This paper presents an experimental approach to determine the load-dependent exponents under three load levels. Load drop in the specimens, as a result of cyclic loading induced changes, is used as the criterion for the damage state. The tests consisted of a series of constant amplitude (standalone) and blocks of sequential variable amplitude cyclic shear tests in a thermo-mechanical micro-scale analyzer. The load-dependent damage exponents were developed for SAC305 (96.5%Sn + 3.0%Ag + 0.5Cu) solder. The result of the study can be used for SAC305 damage accumulation model formulation. Further, the experimental approach can be used to generate additional fatigue data under variable amplitude loads.

    更新日期:2020-01-04
  • A Comprehensive Study on a Stand-Alone Germanium (Ge) Solar Cell
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-22
    V. Baran, Y. Cat, T. Sertel, T. Ataser, N. A. Sonmez, M. Cakmak, S. Ozcelik

    The effect of temperature on the performance parameters [short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and conversion efficiency (η)] of stand-alone germanium (Ge) solar cells has been theoretically investigated. Although JSC increased with increasing temperature, η decreased due to a decrease in VOC and the associated decrease in the FF. The performance parameters JSC, VOC, FF, and η of a fabricated stand-alone Ge solar cell were determined from current–voltage (I–V) measurements. The significant differences between the obtained theoretical and experimental data may be related to both the use of idealized cases in the theoretical studies and the loss mechanisms considered to adversely affect the performance of the fabricated stand-alone Ge solar cell.

    更新日期:2020-01-04
  • Microwave Dielectric Properties of Low-Temperature Co-fired Mg 2 Al 4 Si 5 O 18 -BaCu(B 2 O 5 ) Ceramics
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-27
    Jiji Deng, Huanfu Zhou, Shixuan Li, Chengming Lu, Kangguo Wang, Wendong Sun

    In this work, the sintering temperatures of Mg2Al4Si5O18 ceramics was reduced to ∼ 900°C by adding BaCu(B2O5) (BCB). Mg2Al4Si5O18 reacts with BCB to form the second phase BaAl2Si2O8. As the sintering temperature was 950°C, the second phase transformed from hexagonal BaAl2Si2O8 to monoclinic BaAl2Si2O8 with increasing BCB content. When the BCB content was 15 wt.%, the second phase formed from hexagonal BaAl2Si2O8 to monoclinic BaAl2Si2O8 with increasing sintering temperature. Especially, the sintering temperature of Mg2Al4Si5O18 + 30 wt.%BCB ceramic was reduced to 900°C and the ceramics exhibited good microwave dielectric properties with Q × f = 21,300 GHz, εr= 3.4 and τf = − 30 ppm/°C. The results showed that Mg2Al4Si5O18-BCB ceramics are candidates for LTCC devices.

    更新日期:2020-01-04
  • Microstructures and Mechanical Properties of Sn-58 wt.% Bi Solder with Ag-Decorated Multiwalled Carbon Nanotubes Under 85°C/85% Relative Humidity Environmental Conditions
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-02
    Kyung Deuk Min, Choong-Jae Lee, Hyun-Joon Park, Seung-Boo Jung

    Abstract The mechanical properties of Sn-58 wt.% Bi solder with different amounts (0 wt.%, 0.05 wt.%, 0.1 wt.%, and 0.2 wt.%) of Ag-decorated multiwalled carbon nanotube (MWCNT) nanoparticles under 85°C/85% relative humidity environmental conditions for 0 h to 1000 h was investigated. Sn-58 wt.% Bi solder is a lead-free option for use in solder joints due to its low melting temperature and good creep resistance; however, it is brittle and has reliability issues. Ag-decorated MWCNT nanoparticles were used to improve these weaknesses of Sn-58 wt.% Bi solder. A ball shear test was performed using a bond tester to investigate the solder's mechanical properties. The microstructures of the solder joints and fracture mode were analyzed using a field-emission scanning electron microscope. The results demonstrated that the addition of Ag-decorated MWCNT nanoparticles to Sn-58 wt.% Bi increased the shear strength and fracture energy by approximately 15% and 14%, respectively, compared with Sn-58 wt.% Bi alone. After a high-temperature, high-humidity test for 1000 h, the shear strength and fracture energy of Sn-58 wt.% Bi with 0.1 wt.% Ag-decorated MWCNT nanoparticles were 13% and 21% greater than for Sn-58 wt.% Bi alone.

    更新日期:2020-01-04
  • Mechanism of Thermal Stress Relaxation of Non-bonded Al/Graphite laminated Roll Composite
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-04
    Yuka Yamada, Daiki Matsuhata, Hiroshi Hohjo, Tadayoshi Matsumori

    Miniaturization and high-density packaging of power modules for use in vehicles increases the amount of heat they generate. To prevent damage from heat in such packages, we designed, optimized, and fabricated a composite roll laminated with a non-bonded graphite sheet and Al foil. To find the optimal design of this material, we used finite element analysis to model a non-bonded Al/graphite laminated roll composite, using this simulation to assess how the geometry of its constituent materials influenced its thermal stress. Based on this work, we found that the larger the aspect ratio of the Al foil, the greater the deformability of the composite and the higher its stress relaxation effect. In addition, we found that sandwiching the graphite sheet between the Al foil deforms the foil into a convex shape, and that the Al/graphite laminate composite shows higher thermal stress relaxation than the Al foil does on its own.

    更新日期:2020-01-04
  • Synthesis and Optical Properties of MoS 2 /Graphene Nanocomposite
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-10
    Tran Van Khai, Le Ngoc Long, Mai Thanh Phong, Pham Trung Kien, Le Van Thang, Tran Dai Lam

    In this work, we report a hybrid architecture of layered MoS2/graphene synthesized by an ultrasonic-assisted hydrothermal method at 230°C with a reaction time of 2 h. The microstructure, morphology, chemical composition and optical properties of MoS2/graphene were analyzed by x-ray diffraction, field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), Raman spectroscopy, hard x-ray photoelectron spectroscopy (HAXPES), energy dispersive x-ray (EDX) spectroscopy and photoluminescence measurements. The FESEM results show that the ultrathin MoS2 nanosheets directly deposited on the surfaces of graphene sheets with high density and uniform shape. The TEM and HRTEM images indicate that MoS2 nanosheets with average thickness of ∼ 3–6 nm (6–8 layers) grow vertically on the graphene surface, forming three-dimensional MoS2/graphene hybrid structures. Both XRD and Raman analyses elucidate that the as-grown MoS2 phase of MoS2/graphene composite crystalized in a hexagonal phase (2H-MoS2) with low impurity, which was later confirmed by the HAXPES and EDX. Interestingly, the D-band in the Raman spectrum of MoS2/graphene hybrid samples almost disappears as the 2D-band arises, revealing that defects in the graphene oxide are well repaired under the hydrothermal process. Furthermore, the as-synthesized MoS2/graphene exhibits strong photoluminescence with separately resolved emission peaks in the visible range (∼ 1.75–1.78 eV, ∼ 1.89–1.93 eV and ∼ 1.99–2.05 ,eV) which is a signature of mid-gap states in their optical bandgap compare to that of as-synthesized MoS2. Our synthesis approach is favorable for easy and low-cost preparation of MoS2/graphene composite, rendering the material attractive for various optoelectronic and catalysis applications.

    更新日期:2020-01-04
  • Design of a Tunable Polarization-Insensitive Absorber for L and S Bands Using Active Frequency-Selective Surface
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-22
    Xiaoqing Yang, Huijie Chen, Jiefang Luo, Piqiang Su, Shiyue Wu, Jie Zhou, Jingyu Zhang, Yi Xie, Zhanxia Zhu, Jianping Yuan

    Abstract A tunable polarization-insensitive absorber based on an active frequency-selective surface is proposed for electromagnetic (EM) wave absorption in the L and S bands. The frequency-selective surface consists of a diamond-shaped loop that is interconnected by varactor diodes. The proposed design is significant because of its inclusion of wideband tuning and its ability to easily change from single-band tunable absorption to dual-band absorption. The simulation results demonstrate that the absorption response (> 80%) can vary from 1.62 GHz to 3.66 GHz under the reverse bias voltage, thus creating a tunable range of 125.9%. The absorption region (> 90%) spans from 1.86 GHz to 3.31 GHz and generates a 78% tunable range. The single-band tunable absorber is characterised by an equivalent circuit model to obtain the circuit parameters and predict the absorption frequency. Furthermore, a dual-band absorbing structure is obtained by adding a metasurface directly to the single-layer structure, which can easily be changed from single-band absorption to dual-band absorption by separately controlling the bias voltages of the upper and lower unit cells. The two fabricated prototypes were measured using free-space technology, and the experimental results closely mirror the simulation results. Results show that the proposed structure achieves the dynamic control of EM wave absorption.

    更新日期:2020-01-04
  • Simple Self-assembly Synthesis for Cost-Effective Alkaline Fuel Cell Bi-functional Electrocatalyst Synthesized from Polyethylene Terephthalate Waste Bottles
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-10
    Noha A. Elessawy, Mohamed Elnouby, M. Gouda, Mohamed S. Mohy Eldin, Hassan A. Farag, Abdelaziz H. Konsowa

    The development of bi-functional, non-precious and highly active catalyst has been a key challenge for the commercial application of alkaline fuel cells. In this work, fullerene iron oxide composite, derived from mineral water waste bottles, was used as a catalyst for electrodes in an alkaline fuel cell instead of platinum. The results demonstrate that an oxygen reduction reaction (ORR) was established to proceed through the efficacious four-electron reduction path, and all the reaction steps were found to be spontaneous. Interestingly, fullerene iron oxide composite is a promising electrocatalyst with bi-functional activity for ORR and oxygen evolution reaction in addition to achieving good cycling stability compared to platinum in the alkaline electrolyte.

    更新日期:2020-01-04
  • Synthesis of Zinc Oxide Nanoparticles Through Hybrid Machining Process and Their Application in Supercapacitors
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-02
    Harish Bishwakarma, Alok Kumar Das

    An electrochemical discharge machining process to produce zinc oxide (ZnO) nanoparticles (NPs) under varying voltage and duty factors has been investigated. The morphological and optical characterizations of the generated ZnO NPs were carried out. It was observed that the production rate of NPs and their size increased with an increase in voltage. The ZnO NPs produced at 120 V showed the maximum production rate larger NPs. The field-effect scanning electron microscope images of the NPs revealed a nanorod-like structure, large conical shape rods and hexagonal wurtzite-like structures. The ZnO NPs generated at 120 V and 20% duty factor presented less agglomeration of NPs compared to other NPs generated by varying electrical parameters. The crystal size of the ZnO NPs were found to vary from 31.08 nm to 50.37 nm. The ZnO NPs were also tested for use in a supercapacitor electrode, and the results showed that the specific capacitance of the electrode was 708.75 F/g at a current density of 1 A/g and a retained capacity of 90.42%.

    更新日期:2020-01-04
  • Modified Solution Combustion Synthesis of Nickel-Doped Magnetite Nanoparticles and the Influence of Annealing on Their Optical, Electrical, and Magnetic Properties
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-01
    Mubashir Qayoom, Ruqiya Bhat, Khurshed A. Shah, Altaf Hussain Pandit, Arfat Firdous, Ghulam Nabi Dar

    Abstract In this work, nickel-doped magnetite nanoparticles (NPs) are synthesized by a modified solution combustion method and subsequently annealed at different temperatures. We report the structural, optical, dielectric, electrical, and magnetic properties of nickel-doped magnetite nanoparticles (NPs) annealed at 800°C, 1000°C, and 1200°C for 180 min. X-ray diffraction is utilized to explore the structural properties of the prepared magnetic nanoparticles. The surface morphology indicates that the particles annealed at 800°C and 1000°C are spherical, while particles annealed at 1200°C are polyhedral in shape and have uniform distribution. Energy-dispersive spectroscopy reveals the presence of the elements Ni, Fe, and O in the synthesized nanoparticles. The optical spectra obtained from UV–visible spectroscopy reveal that heat-treated synthesized samples have allowed a direct energy band gap. Also, the optical band gap shows a decreasing trend from 1.736 eV to 1.679 eV, while Urbach energy shows an increasing trend from 0.279 eV to 0.539 eV, with increasing annealing temperature. Photoluminescence spectra show a small redshift in band-edge emission from 433.77 nm to 440.12 nm with an increase in annealing temperature from 800°C to 1200°C. The dielectric studies are carried out at (1) varying frequency (20 Hz–2 MHz) at room temperature and (2) varying temperature (100–400 K) at constant frequency of 100 kHz. Both temperature- and frequency-dependent dielectric studies show an increase in the dielectric constant and dielectric loss with an increase in annealing temperature. Also, the conductivity increases with increased temperature in all studied samples, indicating semiconducting behavior, and increased conductivity is observed with increased annealing temperature. The conductivity behavior follows Mott's law, confirming the variable-range hopping mechanism in all samples. Magnetic measurements show high coercivity of 199.12 Oe and high remanent magnetization of 27.35 emu/g at lower annealing temperature. Thus, the magnetic properties of the synthesized ferrite nanoparticles can be tuned by adjusting particle size through annealing temperature.

    更新日期:2020-01-04
  • Effect of Simultaneous Replacement of Fe with Zr and Ni in a Mechanically Alloyed Multicomponent Fe-Based Amorphous Alloy
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-26
    Zahra Allafe Razzaghi, Abbas Kianvash, Abolfazl Tutunchi

    In this study, Fe-based amorphous powder with a composition of Fe40 Ni25Zr10Si10B15 (compound Q) was prepared by a partial replacement of Fe with Zr and Ni in a Fe75Si10B15 (compound P) via a mechanical alloying route. This substitution led to a decrease in amorphization time and consequently a significant improvement in thermal stability. The structure and thermal properties of the prepared powders were investigated by x-ray diffraction (XRD) pattern and differential scanning calorimetry (DSC), respectively. XRD and DSC results revealed that complete amorphization is achieved after 50 h of milling and glass forming ability width (ΔTx) increases from 50°C to 66°C by substitution of Fe with Zr and Ni in compound P. Magnetic properties of the samples, investigated by vibrating sample magnetometry, indicated that in spite of a negligible decrease in saturation magnetization (Ms) by Fe replacement with Zr and Ni, the coercivity (Hc) shows a positive response to this change as a soft magnetic material, decreasing from 35 Oe to 15 Oe.

    更新日期:2020-01-04
  • Study of E-Mode AlGaN/GaN MIS-HEMT with La-silicate Gate Insulator for Power Applications
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-20
    Kuan Ning Huang, Yueh-Chin Lin, Jia-Ching Lin, Chia Chieh Hsu, Jin Hwa Lee, Chia-Hsun Wu, Jing Neng Yao, Heng-Tung Hsu, Venkatesan Nagarajan, Kuniyuki Kakushima, Kazuo Tsutsui, Hiroshi Iwai, Chao Hsin Chien, Edward Yi Chang

    Abstract An enhancement-mode (E-mode) AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) with La2O3/SiO2 gate insulator is investigated for high power application. The La2O3/SiO2 composite oxide formed amorphous La-silicate after post deposition annealing. Good oxide film quality and excellent La-silicate/AlGaN interface properties were achieved as evidenced by the capacitance–voltage (C–V) curves and hysteresis effect of the La-silicate on AlGaN/GaN metal–oxide–semiconductor capacitors. As a result, the E-mode AlGaN/GaN MIS-HEMT with La-silicate gate insulator shows good threshold voltage (Vth) stability and demonstrated only slightly increase in the dynamic on-resistance (Ron) after high drain bias stress test. The device also exhibits high current density of 752 mA/mm, high maximum transconductance of 210 mS/mm, low subthreshold swing of 104 mV/decade, and ION/IOFF = 107 when tested at VDS = 10 V. Furthermore, low on-resistance of 7.6 Ω mm, high breakdown voltage of 670 V, and excellent delay time of 4.2 ps were achieved, demonstrating the La-silicate MIS-HEMTs have the potential to be used for power electronic applications.

    更新日期:2020-01-04
  • First-Principles Modeling of Oxygen Adsorption on Ag-Doped LaMnO 3 (001) Surface
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-26
    A. U. Abuova, Yu. A. Mastrikov, E. A. Kotomin, S. N. Piskunov, T. M. Inerbaev, A. T. Akilbekov

    Abstract The density functional theory (DFT) method has been used to calculate oxygen adsorption on the Ag-doped MnO2- and LaO-terminated (001) LaMnO3 surfaces. The catalytic effect of Ag doping is revealed by comparison of the adsorption energies, electron charge redistribution, and interatomic distances for the doped and undoped surfaces. Adsorption of Ag on the MnO2-terminated surface increases the adsorption energy for both atomic and molecular oxygen. This increases the oxygen surface concentrations and could improve the cathode efficiency of fuel cells. The opposite effect takes place at the LaO-terminated surface. Due to the large adsorption energies, adsorbed oxygen atoms are immobile and the oxygen reduction reaction rate is controlled by the concentration and mobility of oxygen vacancies.

    更新日期:2020-01-04
  • Facile Synthesis, Optical–Dielectric–Electrical Studies on Carbon-Coated ZnO: An Effect of Gelatin
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    M. Aslam Manthrammel, Mohd. Shkir, H. Y. Zahran, I. S. Yahia, V. Ganesh, S. Alfaify

    Carbon (C)-coated zinc oxide (ZnO) nanoparticles (NPs) having different sizes and morphologies were successfully synthesized by a flash combustion biomimetic approach using different contents of gelatin as the medium. Structural and vibrational studies indicate that the NPs are grown in a hexagonal wurtzite structure. The amount of gelatin content has a strong effect on the growth mechanism and the physical and optical properties. The presence of C in the ZnO was clearly confirmed by Raman analysis in which the Raman bands corresponding to the presence of C were observed at ∼ 1343 cm−1 (G-band), 1580 cm−1 (D-band), and 2700 cm−1 (G′-band). At low concentrations, the NPs grew in the shape of spherical aggregates which arranged themselves in the form of a spherical flower-like structure. At 1 g of gelatin content, the spherical flower-like structure disappeared to be distributed at 3 g of gelatin content into a uniform planar spherical NP arrangement in the shape of a multi-aggregated cauliflower-like structure. At higher concentrations, the NPs rearranged themselves in the shape of a hexagonal disk or a prism-like structure. The band gap values were found to decrease with increasing gelatin content and were in the range of 3.18–3.26 eV, though it showed the dependency on the size, shape and presence of C in ZnO. Studies of the dielectric properties and ac conductivity on the prepared NPs were also carried out.

    更新日期:2020-01-02
  • Study of Photocatalytic Properties of Ag/AgCl-Decorated Soybean Protein Knitting Fabric Against Acid Blue 260 Dye by Factorial Design
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    N. F. Andrade Neto, R. L. B. Cabral, A. A. G. Santiago, M. R. D. Bomio, F. V. Motta, J. H. O. Nascimento

    Abstract Photocatalytic materials have been the focus of several studies due to their excellent optical photoexcitation properties for waste treatment. However, their use promotes the generation of inorganic secondary waste, due to their nanometric grain size, which can cause several environmental hazards. The optimization and immobilization of such photocatalysts for treatment after the catalytic process have thus attracted much attention. In this work, Ag/AgCl nanoparticles were immobilized by hydrothermal treatment on soybean knitted fabric. The photocatalytic activity of the resulting Ag/AgCl-functionalized soybean knitted fabric was estimated based on the reduction of the concentration of Acid Blue 260 dye. The response surface factorial design methodology was applied, varying the Ag/AgCl concentration, nanocatalyst immobilization time, and hydrothermal process temperature, to analyze the individual effect of and interaction between the variables, besides establishing a mathematical model of the process. The photocatalytic results showed that addition of Ag/AgCl to the fabric favored its use and reuse for the degradation of the Acid Blue 260 dye. The mathematical model together with the response surfaces showed that the residence time in the hydrothermal bath was the most significant variable in terms of the dye reduction, favoring this advanced treatment method.

    更新日期:2020-01-02
  • Fabrication of Attapulgite/Multi-walled Carbon Nanotube Aerogels As Anode Material for Lithium Ion Batteries
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    Ye Lan, Dajun Chen

    Porous silica-based anode materials with high theoretical specific capacity and abundant reserves have attracted popular attention for application in lithium ion batteries (LIBs). However, poor electrochemical conductivity and mechanical performance hinder the development of silica-based anode materials. In this work, attapulgite/multi-walled carbon nanotube (AT/CNT) composite anode materials were prepared. The structural features of AT/CNT composite aerogels were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). because of the excellent conductivity and porous pathways of AT/CNT anode material, the reversible specific capacity of AT/CNTs containing 0.5 wt.% CNTs (AT-0.5) with a mass loading of 0.67 mg cm−2 was 303.6 mAh g−1 at 0.1 A g−1 after 50 cycles, and a coulombic efficiency of AT-0.5 was 99.1%. The green LEDs were lit by the assembled battery of AT-0.5. The electrochemical results demonstrated that AT/CNT anode materials possessed practical application values for energy storage. Moreover, the preparation method of AT/CNT anode materials is efficient and environmentally friendly.

    更新日期:2020-01-02
  • Rheological Behavior and Thermal Conductivities of Emulsion-Based Thermal Pastes
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    Ali Yazdan, Jizhe Wang, Ce-Wen Nan, Liangliang Li

    The role of thermal interface materials (TIMs) has become substantial due to their critical applications in electronic devices for effective heat dissipation. Dimethyl silicone oil-based thermal pastes are widely used as TIMs because they can provide an intimate bonding between the heat sink and the electronic chip; however, the thermal conductivities of typical silicone oil-based thermal pastes are low. In this study, we prepared thermally conductive emulsion-based thermal pastes with two kinds of boron nitride (BN) fillers and investigated their rheological behavior and thermal conductivities. The emulsion was composed of dimethyl silicone oil, n-butanol, and sorbitan monooleate (Span 80) as an emulsifier. The fillers were boron nitride fibers (BNFs) and boron nitride nanosheets (BNNSs). The viscosity, storage modulus, and loss modulus of the emulsion-based pastes were smaller than those of the corresponding silicone oil-based ones. The thermal conductivities of the emulsion based pastes were larger than those of the silicone oil-based ones because of their lower viscosity and higher baseline thermal conductivity. The pastes with BNNSs had larger thermal conductivities in comparison with the corresponding ones with BNFs. To further enhance the thermal conductivity, BNNSs were coated with two silane coupling agents, 3-aminopropyl-triethoxy silane (KH550) and 3-(Trimethoxysilyl)propyl methacrylate (KH570), and then introduced into the emulsion. The maximum thermal conductivity was 1.04 W m−1 K−1 for the emulsion-based paste with KH550-coated BNNSs at a filler loading of 39 vol.%, which was a ∼ 7-fold increase in comparison with that of neat silicone oil (0.13 W m−1 K−1).

    更新日期:2020-01-02
  • Optical Properties of the Oxygen Vacancy in KNbO 3 Crystal
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    Xuping Jiao, Tingyu Liu, Yazhou Lu, Qiuyue Li, Rui Guo, Xueli Wang, Xun Xu

    The defect formation energy of an oxygen vacancy with different charge states (0, +1, +2) has been studied. The finite-size correction scheme (FNV) for the alignment of the defect formation energy is available. The corresponding correction energies are in the range of 0.32–1.29 eV. On the basis of the corrected defect formation energy, fairly accurate optical spectrum line shapes of F and F+ centers are obtained, taking account of electron–phonon coupling. The calculated absorption and luminescence peaks are located at 2.73 eV and 2.62 eV for the F center, and 2.44 eV and 2.25 eV for the F+ center, respectively, which agree well with experimental results. Finally, the result proves that the F+ center is the key point involved in the body color change of the KNbO3 crystal.

    更新日期:2020-01-02
  • Long-Term Stability of the Colossal Seebeck Effect in Metallic Cu 2 Se
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    Dogyun Byeon, Robert Sobota, Saurabh Singh, Swapnil Ghodke, Seongho Choi, Naoto Kubo, Masahiro Adachi, Yoshiyuki Yamamoto, Masaharu Matsunami, Tsunehiro Takeuchi

    Determination of thermoelectric properties is rather a challenging task, especially during a phase transition, where a drastic change in magnitude of thermoelectric properties is generally observed. In this study, we performed a precise measurement of the Seebeck coefficient on Cu2Se, which was recently reported to possess a colossal Seebeck coefficient with metallic electrical conductivity during a structural phase transition. We confirmed that the colossal Seebeck effect was stable over a long period of time, as high as −0.9 mV under an applied temperature gradient of 1 K. This fact clearly proved that the colossal Seebeck effect observable in metallic Cu2Se is potentially usable for a variety of thermoelectric applications.

    更新日期:2020-01-02
  • Temperature-Dependent Crystallization of Ga 2 O 3 for Ultraviolet Photodetectors
    J. Electron. Mater. (IF 1.676) Pub Date : 2020-01-02
    Jinjie Wu, Chao Li, Ximing Rong, Peijiang Cao, Shun Han, Yuxiang Zeng, Wenjun Liu, Deliang Zhu, Youming Lu

    As an n-type oxide semiconductor, Ga2O3 shows great promise in solar-blind ultraviolet (UV) photodetectors due to its adequate band gap, high absorption coefficient, high thermal and chemical stability, high breakdown voltage, and high sensitivity to UV light. In order to investigate the photoresponse of the Ga2O3 photodetector with different crystallization status, we fabricated a series of β-Ga2O3 thin films on a sapphire substrate via pulsed laser deposition with different deposition temperatures from 250°C to 650°C. X-ray diffraction and scanning electron microscopy result showed crystallization enhancement due to the increasing of deposition temperature, and the crystallization procedure started at ∼ 450°C. Optical analysis indicated a blue shift present at the absorption edge (from 4.6 eV to 5.1 eV) with temperature increasing from 450°C to 650°C, showing modulation feasibility in the band gap due to temperature dependence. In addition, all samples showed high transmittance (over 90%) over the entire visible spectrum. Film detectors fabricated by these samples showed high photoresponse and high light/dark current ratio (ILight/IDark) on Ga2O3 deposited at 450°C. Transmission electron microscopy result for film deposited at 450°C showed that the top and bottom regions of films contained both amorphous and crystalline Ga2O3, while there was no crystallization in the middle area of the film, indicating that a combined amorphous-crystalline Ga2O3 film with adequate ratio of crystalline state can significantly enhance the photoresponse while restraining the dark current.

    更新日期:2020-01-02
  • Low Temperature Cu-to-Cu Bonding in Non-vacuum Atmosphere with Thin Gold Capping on Highly (111) Oriented Nanotwinned Copper
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-13
    Yu-Ting Wu, Chih Chen

    Cu-to-Cu bonding has drawn a lot of attention as it not only has excellent electrical and thermal properties but also excellent electromigration resistance. It is believed to be a next-generation technology of IC packaging and it will help keep Moore’s law effective. According to previous studies, copper direct bonding using nanotwinned copper can reduce the bonding temperature to 150°C but still requires a vacuum atmosphere. This study employed an E-gun to plate a gold layer on nanotwinned copper thin films in order to prevent oxidation. With the aid of the thin gold layer, we can prevent the oxidation of Cu surfaces and reduce the surface roughness. In this way, we achieved bonding at 200°C in N2 and 250°C in ambient pressure with a low bonding pressure of 0.78 MPa.

    更新日期:2020-01-02
  • Effect of Component Flexibility During Thermal Cycling of Sintered Nano-Silver Joints by X-ray Microtomography
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-07-30
    Jason J. Williams, Irene Lujan Regalado, Leo Liu, Shailesh Joshi, Nikhilesh Chawla

    Abstract X-ray tomography was used to monitor damage evolution in nano-silver sintered joints during thermal cycling. Samples consisted of a silicon die joined to a direct bond copper substrate by sintering nano-silver paste. The amount of observable damage was significantly affected by the amount of allowable warping during the thermal cycling tests. By fully constraining the sample from flexing during thermal cycling, all observable damage was eliminated.

    更新日期:2020-01-02
  • Correction to: Thin Film of Perovskite (Mixed-Cation of Lead Bromide FA 1−x MA x PbBr 3 ) Obtained by One-Step Method
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-04
    B. Slimi, M. Mollar, B. Marí, R. Chtourou

    In the original article, there is an error in the article title. The article title is corrected as reflected here.

    更新日期:2019-12-21
  • Thermal Interface Materials
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-21
    D. D. L. Chung

    Abstract Cooling is critically needed for reliability, power and further miniaturization of microelectronics. Heat sinks are obviously important for heat dissipation. However, thermal interface materials (TIMs) are needed to improve thermal contacts, such as the thermal contact between a heat source (e.g., a microprocessor) and a heat sink. This commentary is directed at clarifying some misconceptions related to the design and testing of TIMs.

    更新日期:2019-12-21
  • Effects of Calcining Temperature on Structure and Dielectric and Ferroelectric Properties of Sol-Gel Synthesized Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 Ceramics
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-05
    X. W. Wang, B. H. Zhang, G. Feng, L. Y. Sun, Y. C. Shi, Y. C. Hu, J. Shang, S. Y. Shang, S. Q. Yin, X. E. Wang

    Abstract Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) powders were prepared by sol-gel process followed by calcining at different temperatures varying from 600°C to 950°C, and the BCZT ceramics were then prepared using the as-synthesized powders. The effect of calcining temperature on structure, dielectric properties and ferroelectric properties of BCZT ceramics were studied. Impurity was observed in powders calcined at 600°C, and single-phase perovskite structure was obtained when calcining temperature increased to 650°C, which was significantly lower than that of the solid-state reaction. The high-density ceramics with homogenous microstructure were obtained by sintering at 1300°C for 2 h. The dielectric constants as a function of measuring temperature exhibited a diffuse phase transition peak. With the increase of calcining temperature, the slimmer P–E loops were obtained, and the BCZT ceramic calcined at 950°C exhibits a relatively high dielectric constant (εr = 2013) and low dielectric loss (tan δ = 0.020) at 1 kHz and room temperature.

    更新日期:2019-12-21
  • Impedance Spectroscopy and Conduction Behavior in CoFe 2 O 4 -BaTiO 3 Composites
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-21
    S. Shankar, O. P. Thakur, M. Jayasimhadri

    Magnetoelectric composites combining ferromagnetic cobalt ferrite (CFO) and ferroelectric barium titanate (BT) are prepared using conventional solid-state reaction. Dielectric measurements reveal that CFO and CFO-BT composites exhibit Maxwell–Wagner polarization and temperature-dependent relaxation originating due to the presence of ions/defects vacancies. Prominently, CFO-30%BT composite showed an unexpected low dielectric loss ≈ 0.5 above 1 kHz and has potential for device application. Impedance spectroscopy confirms the thermally activated relaxation mechanism and high impedance behavior in the samples. Modulus analysis affirms the statistically distributed non-Debye-type behavior existing in CFO-BT composites. The electric conductivity takes place via correlated barrier hopping in CFO and CFO-10BT composite and overlapping large polaron tunneling in CFO-30BT composite. The addition of BT in CFO initiates the structural modification and results in conductivity cross-over with improved conductivity. These results are useful for exploring devices based on CFO-BT composites.

    更新日期:2019-12-21
  • Impact of Sn 4+ Substitution at Cr 3+ Sites on Thermoelectric and Electronic Properties of p -Type Delafossite CuCrO 2
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-12
    Sakwiboon Jantrasee, Chesta Ruttanapun

    Abstract The effects of Sn4+ substitution at Cr3+ sites on the thermoelectric and electronic properties of p-type delafossite CuCrO2 have been studied. CuCr1−xSnxO2 (x = 0.01, 0.03) samples were prepared via conventional solid-state reaction. The Seebeck coefficient results confirmed that all the samples exhibited p-type conduction. X-ray photoelectron spectroscopy verified the presence of Sn4+ ions and the appearance of mixed-state Cr3+/Cr2+ ions. The experimental results revealed that addition of Sn impacted the electrical conductivity due to the mixed Cu1+/Cu2+ states while the Seebeck coefficient was affected by the mixed Cr3+/Sn4+ states. The electrical conductivity was governed by the polaron hopping mechanism, and the large Seebeck coefficient was controlled by the spin and orbital degeneracy of the mixed Cr3+/Sn4+ ions. The electrical conductivity activation energy values were 0.410 eV and 0.407 eV while the thermal activation energy values were 0.208 eV and 0.160 eV, for x = 0.01 and 0.03, respectively. The results confirm that Sn4+ substitution at Cr3+ sites impacted the Seebeck coefficient and electronic behavior of delafossite CuCrO2 oxide even for low dopant levels of x = 0.01 and 0.03, resulting in p-type conduction and optically conducting materials.

    更新日期:2019-12-21
  • The Effect of SnO 2 and ZnO on the Performance of Perovskite Solar Cells
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-14
    Elham Karimi, Seyed Mohamad Bagher Ghorashi

    Abstract The efficiency of perovskite solar cells is studied through the Analysis of Microelectronic and Photonic Structures (AMPS) and the Solar Cell Capacitance Simulator (SCAPS) simulation software programs. The programs serve to determine how the thickness of HTM, ETM and perovskite absorber layers affects the performance of solar cells. An investigation is also conducted on how temperature, electron density concentration and perovskite defect density affect the fill factor (FF), performance (PCE), short-circuit current density (JSC), and open-circuit voltage (VOC). Then, J–V characteristics are calculated using ZnO and SnO2 as two types of ETM. As a result, optimal values are achieved for the thickness of HTM, ETM and absorber layers. It is also indicated that an increase in the defect density of perovskites can reduce the performance of solar cells. Another important finding of the study is that ZnO can possibly replace the expensive SnO2 for better ETM conversion performance.

    更新日期:2019-12-21
  • Third Order Nonlinear Optical Properties of Piperazine Calcium Chloride (PCC) Crystal to Enhance the Optical Device Applications
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-16
    R. U. Mullai, D. Sivavishnu, R. ArulJothi, G. Vinitha, S. Gopinath, S. Vetrivel

    Abstract Optical quality crystal piperazine calcium chloride (PCC) was synthesized and grown successfully by slow evaporation solution growth technique at room temperature. Well-defined Bragg’s peak in powder x-ray diffraction analysis confirms the crystalline nature of the grown sample PCC. Unit cell parameters values that were calculated using single crystal x-ray diffraction analysis confirms that the crystal belongs to the monoclinic crystal system. The wave number band assignments of the synthesized material are identified by using Fourier Transform Infrared spectroscopy. Linear optical study shows that the UV cut-off wavelength was found to be 260 nm and also the optical energy band gap was calculated using UV data. Maximum emission spectra of wavelength 441 nm and 477 nm are evident in the emission of blue laser from the Florescence (PL) spectra. The dielectric constant and dielectric loss of the grown PCC crystal were analyzed as a function of different frequencies for different temperatures. As grown PCC crystal was subjected to thermal analysis to find the weight-loss and decomposition point using TG–DTA curve. Work hardening coefficient of as grown PCC crystal was 2.36, which is evidence that the crystal belongs to soft category material and also the mechanical parameters are calculated. Third order nonlinear optical property was analyzed using Z-scan technique, which shows that the crystal PCC obeys the third harmonic generation properties to enhance the optical device applications.

    更新日期:2019-12-21
  • Effect of Multiple Reflowing Processes on Interfacial Reactions and Mechanical Properties between Sn-9.0 wt.%Zn, Sn-3.0 wt.%Ag-0.5 wt.%Cu Solders and Ag Substrate
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-30
    Chia-Yu Liu, Po-Cheng Kuo, Chih-Ming Chen, Jia-Ying Dai, Yee-Wen Yen, Alberto S. Pasana

    The effect of multiple reflowing processes on interfacial reactions and mechanical properties of the Sn-9.0 wt.%Zn (SZ)/Ag and Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC)/Ag couples was investigated in this study. The SZ/Ag and SAC/Ag couples were reflowed at 240°C for 10 min in one up to five times. After reflowing, all couples were quenched in icy water and air-cooling conditions. The experimental results revealed that the AgZn3, Ag5Zn8, and AgZn phases were formed in the SZ/Ag couple. The thin AgZn3 layer was observed when the SZ/Ag couple was quenched in icy water. When the number of reflows was increased, a rod-shaped Zn phase gradually became a fine needle-shaped Zn phase. Only the Ag3Sn phase was formed in the SAC/Ag couple. The growth mechanism of the intermetallic compound was diffusion-controlled in both reaction couples. A brittle fracture was observed in the SZ/Ag solder joint. The fracture surface showed the ductile and slightly brittle failure in the SAC/Ag solder joint.

    更新日期:2019-12-21
  • Near-Net-Shape Fabrication of Thermoelectric Legs by Flash Sintering
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-29
    Masashi Mikami, Yoshiaki Kinemuchi, Kazuya Kubo, Naoki Uchiyama, Hidetoshi Miyazaki, Yoichi Nishino

    Abstract This study examines the near-net-shape fabrication, by flash sintering, of a sintered body for use in a thermoelectric module. Gas-atomized Fe2VAl powder was sintered with a current feed, for a duration on the order of seconds, using an apparatus specially devised for flash sintering. This produced sintered bodies in columnar form, with a diameter and height on the order of millimeters, which can be used for constructing thermoelectric modules without the need for a machining process, such as cutting or dicing. Although a slight reduction in density is observed, the crystal structure is unaffected by rapid heating and cooling. The magnitude of electrical and thermal conductivity is reduced, while the value of Seebeck coefficient is identical to that of a sample sintered by using conventional current sintering at 1373 K for 10 min. The significantly shorter sintering time can reduce energy consumption to less than 1 Wh, compared with the several hundred Wh required for conventional current sintering. Although it is still necessary to optimize the sintering conditions to overcome the reduction in density, the significant energy-conservation benefits of flash sintering have great practical appeal, especially for fabricating sintered bodies constituting thermoelectric power generation devices used for energy recovery.

    更新日期:2019-12-21
  • Synthesis of Ag Nanoparticle-Decorated ZnO Nanorods Adopting the Low-Temperature Hydrothermal Method
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-07
    Kanchana Shahi, R. S. Singh, Jai Singh, Maria Aleksandrova, Ajaya Kumar Singh

    Vertically aligned and highly dense Zinc oxide (ZnO) nanorods (NRs) have been successfully synthesized by a two-step hydrothermal method and decorated by silver (Ag) nanoparticles (NPs) via a dip coating technique. Absorption spectra indicate the presence of metal Ag NPs. The photoluminescence (PL) spectrum of as-grown ZnO nanorods shows ultra violet (UV) emission centered around 390 nm and a sharp defect-related emission peak around 580 nm. The presence of Ag NPs on the ZnO NRs shows a significant red shift in PL peak position in the visible region and a complete quenching of UV emission. The changes in UV–Vis and PL spectra of ZnO NRs decorated with Ag metal NPs are studied and discussed.

    更新日期:2019-12-21
  • Ab-Initio Simulations of Monolayer InSe and MoS 2 Strain Effect: From Electron Mobility to Photoelectric Effect
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-13
    Kun Luo, Wen Yang, Yu Pan, Huaxiang Yin, Chao Zhao, Zhenhua Wu

    Abstract In this paper, we present a comprehensive study of the basic electronic properties of two typical two-dimensional materials, monolayer InSe and MoS2 in the presence of various in-plane strains. Our results demonstrate that both materials exhibit similar trends in the variation of band gaps with strain modulations. With the application of strain, a transition between indirect and direct band gap is observed in monolayer InSe. Otherwise, on the application of strains, the band edge of MoS2 shows an excursion from K point and the electron mobility can be enhanced by compressive strain. The electron mobility of InSe can be boosted by about 10% and thus up to \( 2.24 \times 10^{3} \;{\hbox{cm}}^{2} /\left( {{\hbox{V}}\;{\hbox{s}}} \right) \), which approaches one order of magnitude later than that of MoS2. After rebuilding the structure, we introduce illumination to our two-probe system and measure the response. The high responsivity and excellent strain flexibility of InSe rather than MoS2 make it superior as a candidate for the next generation ultrathin electronic and optoelectronic devices.

    更新日期:2019-12-21
  • Upconversion Luminescence and Optical Temperature-Sensing Properties of LaNbO 4 :Yb 3+ /Er 3+ Phosphors
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-07
    Xuerui Cheng, Xingbang Dong, Ke Peng, Huanjun Zhang, Yuling Su, Liying Jiang

    In recent years, upconversion (UC) luminescence has attracted considerable attention because of its potential application in temperature measurement. In this work, LaNbO4:Er3+/Yb3+ phosphors are synthesized using a solid-state method. The x-ray diffraction patterns show that the phosphors obtained exhibit a single monoclinic structure, and doping does not change the crystal structure. Intense green and red emissions are observed upon 980-nm excitation. The emission intensity varies with the doping concentration, and the best doping concentrations are 1 mol.% and 10 mol.% for Er3+ and Yb3+ ions, respectively. The possible luminescence mechanism is investigated based on the UC emission dependence on pump power. The temperature-sensing ability is also investigated based on the fluorescence intensity ratio between two thermally coupled levels 2H11/2 and 4S3/2. The maximum sensitivity achieved is 0.81% K−1 at around 430 K, suggesting that the phosphor is a potential candidate for temperature sensing applications.

    更新日期:2019-12-21
  • Enhanced Thermoelectric Performance of n -Type Polycrystalline SnSe via MoCl 5 Doping
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-12
    Tong Shen, Kang Yin Li, Zi Jie Chen, Hai Fei Wu, Jian Xiao Si

    n-Type polycrystalline SnSe0.95-x%MoCl5 (x = 0.5, 1.0, 1.5, 2) samples have been synthesized by melting and hot-pressing. The effect of MoCl5 doping on thermoelectric properties is investigated. The multipoint defects of Clse and Mosn increased the carrier concentration from 5.3 × 1017 cm−3 (p-type) in undoped SnSe to 1.76 × 1019 cm−3 (n-type) in SnSe0.95-1.5%MoCl5 sample, which leads to increased electrical conductivity. Moreover, the multipoint defects enhanced the phonon scattering and resulted in a suppression of the thermal conductivity. As a result, a peak value ZT of 0.66 was obtained at 773 K for SnSe0.95-1%MoCl5. These results show that MoCl5 could be an effective dopant for improving the thermoelectric performance of n-type SnSe.

    更新日期:2019-12-21
  • Magnetic and Structural Properties of Exchange Coupled Heusler Alloy NiO/Co 2 FeAl Interfaces with n -and p -Type Silicon Substrates
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-11
    Arvind Kumar, Neelabh Srivastava, P. C. Srivastava

    Exchange coupled structures of half metallic ferromagnets, Heusler Alloy (FM), Co2FeAl (CFA) and antiferromagnet (AF), NiO were fabricated by electron beam evaporation technique on n- and p-type Si substrates. These fabricated bilayer structures were further characterized for structural, morphological and magnetic point of views using x-ray diffraction (XRD), atomic/magnetic force microscopy (AFM/MFM) and vibrating sample magnetometer (VSM) techniques. Structural study shows the presence of CFA alloy and NiO phase. Surface morphology shows the granular feature of the top surface with grain size of 200–300 nm due to clustering of smaller grains. Smaller sized magnetic domains have been observed for the structures. Hysteresis behaviour of NiO/CFA/Si structures shows the ferromagnetic behaviour for in-plane orientation with negligible exchange bias whereas a significant exchange bias for out of plane orientation has been observed. The observed result could be understood due to surface roughness and arrangements of spins near the interface of ferromagnetic and anti-ferromagnetic layers.

    更新日期:2019-12-21
  • Investigation of Quaternary Barrier InAlGaN/GaN/AlGaN Double-Heterojunction High-Electron-Mobility Transistors (HEMTs) for High-Speed and High-Power Applications
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-22
    P. Murugapandiyan, A. Mohanbabu, V. Rajya Lakshmi, Mohammed Wasim, K. Meenakshi Sundaram

    Abstract We report direct current (DC) and microwave performance of a 50-nm gate length (Lg) quaternary-based InAlGaN/GaN/AlGaN high-electron-mobility transistor (HEMT) on SiC substrate with SiN passivation and by using a T-gate. The proposed HEMT structure is simulated using industry-standard Synopsys Sentaurus technology computer-aided design (TCAD). The regrown n++ GaN source/drain ohmic contacts show a peak drain current density (Idmax) of 2.9 A/mm along with low on-resistance of 0.49 Ω mm. A record power gain cut-off frequency (fmax) of 425 GHz along with current gain cut-off frequency (ft) of 310 GHz are obtained by the substantial reduction in the device's intrinsic and extrinsic parasitic resistances and capacitances. A very thin 7-nm In0.13Al0.83Ga0.04N quaternary barrier with an AlGaN back-barrier structure effectively mitigates the short-channel effect with an improved breakdown voltage (VBR) of 38 V. The prominent DC and microwave characteristics of the proposed HEMT make it an appropriate candidate for next-generation high-power millimeter-wave electronics.

    更新日期:2019-12-21
  • Effect of Heating Rate on Bulk Density and Microstructure in Bi 2 Te 2.7 Se 0.3 Sintering
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-10-30
    Chang Hyun Lee, Hyo Soon Shin, Dong Hun Yeo, Sahn Nahm

    Bi-Te is a thermoelectric material used at room temperature. It is typically fabricated as a single-crystal ingot, making processing difficult and material loss very high. Pressureless sintering processes have been studied to address these issues; however, they typically result in lower-density material. Methods such as hot isostatic pressing and spark plasma sintering have mainly been studied. However, there has been limited research on pressureless sintering without additional steps such as pressurization or charging. The aim of this study is to obtain a dense Bi2Te2.7Se0.3 sintered body by combining rapid sintering with air sintering by modifying a typical sintering furnace. The effect of heating rate on densification and phase change was also investigated. Bi2Te2.7Se0.3 powder was first synthesized by the mechanochemical method. The synthesized powder was then heated at a rate of 5°C/s to 20°C/s and finally sintered at a temperature of 570°C for 10 min in H2/N2 mixture under Te-rich conditions. These conditions produced a sintered body with relative density of at least 90% of the theoretical density, and a bulk density of 6.98 g/cm3 was obtained when temperature was increased at a rate of 20°C/s. Observation of the microstructure showed that porosity decreased as the heating rate was increased. The results of this study confirm that the heating rate during rapid sintering can affect the density of the sintered body.

    更新日期:2019-12-21
  • Enhanced Charge Transport and Corrosion Protection Properties of Polyaniline–Carbon Nanotube Composite Coatings on Mild Steel
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-12
    T. Rajyalakshmi, Apsar Pasha, Syed Khasim, Mohana Lakshmi, M. V. Murugendrappa, Nacer Badi

    We report on the synthesis and characterization of carbon nanotube (CNT)-doped polyaniline (PANI) composites for enhanced corrosion protection of steel with improved electrical properties. PANI–CNT nanocomposites were prepared through in situ polymerization of aniline in the presence of CNTs. Synthesized nanocomposites were characterized by several analytical methods such as Fourier transform infrared spectroscopy, x-ray diffraction, micro-Raman spectroscopy, and scanning electron microscopy in order to understand the structural, morphological, and molecular aspects of the composites. The doping of CNTs in PANI matrix drastically enhanced the alternating current/direct current (AC/DC) conductivities as well as the dielectric attributes and impedance spectroscopy of the composites. The anticorrosion studies of the prepared composites were performed by using open-circuit potential analysis and potentiodynamic measurements. Compared to stainless steel, PANI–CNT nanocomposites demonstrated excellent anticorrosion behavior. The obtained results showed that 25 wt.% of CNT-doped PANI composite exhibits excellent anticorrosion properties due to electron transmission and passive catalysis.

    更新日期:2019-12-21
  • Ultrasound-Assisted Method for Preparation of Ag 2 S Nanostructures: Fabrication of Au/Ag 2 S-PVA/n-Si Schottky Barrier Diode and Exploring Their Electrical Properties
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-11-12
    Y. Badali, Y. Azizian-Kalandaragh, Ehsan A. Akhlaghi, Ş. Altındal

    Abstract Au/n-Si metal/semiconductor (MS) Schottky barrier diodes with and without (Ag2S-PVA) interlayer were prepared by the ultrasound-assisted method and their electric and dielectric properties were examined by using current–voltage (I–V) and capacitance–voltage (C–V) measuring devices. The structural, optical and morphological characteristics of the (Ag2S-PVA) were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Visible spectroscopy. The observed peaks in the XRD pattern are related to the α-phase of silver sulfide. The UV–Visible spectrum of (Ag2S-PVA) shows the quantum confinement and SEM image proves the grain size in nano-scale. The ideality factor (n) and barrier height (BH) at zero bias (ΦB0(I–V)) were acquired from the I–V data. On the other hand; Fermi energy (EF), donor concentration atoms (ND), and BH (ΦB(C–V)) values were obtained from the reverse bias C–V data. The voltage-dependent resistance profile (Ln(Ri)–V) was obtained by applying Ohm’s law and also by the Nicollian–Brews methods. Also, considering the voltage-dependent n and BH, Nss–(Ec–Ess) profile was acquired from the forward biases I–V characteristics. Depending on high, intermediate and low biases ln(I)–Ln(V) curves have three linear regions with distinct slopes for MS and MPS structures. The predominant current-transport mechanisms were obtained in related regions via trap-charge limited current and space-charge limited current, respectively. These outcomes indicate that the (Ag2S-PVA) interlayer enhanced the performance of the diode considerably in terms of high rectifier rate (RR), shunt resistance (Rsh), and low surface states (Nss) and series resistance (Rs). Thus, the (Ag2S-PVA) interlayer can be used in MS type diode instead of a traditional insulator layer.

    更新日期:2019-12-21
  • Evaluation of Cu-TSV Barrier Materials as a Solution to Copper Protrusion
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-20
    Yazdan Zare, Yasushi Sasajima, Jin Onuki

    Abstract The development of three-dimensional large-scale integration is technically contingent upon the optimization of through-silicon via (TSV) performance. One of the intriguing challenges in the fabrication of Cu-TSV is the minimization of copper protrusion after heat treatment of TSV or any thermal cycle. Plastic behavior of copper in the temperature range of the annealing process causes the copper to protrude out of the via and damage the upper layers. Since using copper and silicon as the main constituents of the Cu-TSV is inevitable, the best solution to the copper protrusion seems to be confined to finding the best material for the barrier. The barrier is basically a liner preventing copper diffusion into the silicon. However, the material of the barrier must be selected wisely in order to assign multiple tasks to it, including the prevention of the copper protrusion. In this paper, the effects of the barrier properties on copper protrusion are evaluated, and the most proper materials for the barrier of Cu-TSV are suggested. A physical explanation of the protrusion phenomenon and the way that barrier material can minimize the protrusion are also presented.

    更新日期:2019-12-20
  • Hybrid Graphene Titanium Nanocomposites and Their Applications in Energy Storage Devices: a Review
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-20
    Ivy Heng, Foo Wah Low, Chin Wei Lai, Joon Ching Juan, Sieh Kiong Tiong

    Emissions of natural gas and carbon dioxide due to fossil fuels have become a global issue which influences the development of various technologies. Demand for clean renewable power sources is ever increasing. However, renewable sources are intermittent in nature, which poses a challenge in electricity generation and power load stability. Lately, supercapacitors have attracted remarkable interest in the field of electricity storage due to their ability to store large amounts of electric charge, enabling high power output. Reduced graphene oxide incorporated with titanium dioxide (rGO/TiO2) nanocomposites are well considered as potential supercapattery materials due to their superior mechanical properties, notable strength, and abundance in Nature. rGO carbon material acts as the ion reservoir, facilitating faster electron transfer mobility, whereas mesoporous TiO2 provides a larger surface area and more active sites, which improve the cycling stability and specific capacitance. Literature reports that supercapacitor performance mainly depends on the choice of the electroactive material, electrolyte, and current collector. This review focuses on recent developments in supercapacitor technology, storage mechanisms of different electrodes, a comprehensive discussion of different challenges related to energy storage devices, as well as the formation mechanism of rGO/TiO2 hybrid electrodes.

    更新日期:2019-12-20
  • Electronic Polarizability, Optical Basicity, Thermal, Mechanical and Optical Investigations of (65B 2 O 3 –30Li 2 O–5Al 2 O 3 ) Glasses Doped with Titanate
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-20
    Kh. S. Shaaban, E. A. Abdel Wahab, E. R. Shaaban, El Sayed Yousef, Safwat A. Mahmoud

    Abstract Titanium-doped and titanium-free lithium borate glasses were prepared using a quenching method and high-purity-grade chemical substances. Structural analysis was carried out by Fourier transform infrared (FT-IR) spectroscopy and mechanical measurement. The states of the produced glasses were examined by x-ray diffraction, and the density (ρ) and molar volume (Vm) were determined. The Makishima–Mackenzie model was applied for the prepared glasses. FT-IR confirmed that the concentration of [BO4] was greater than that of [BO3] structural units. These variations confirmed that the compactness of the lithium borate network increased as the concentration of (TiO2/B2O3) increased. The longitudinal (vL) and shear (vT) velocities of the samples with varying concentrations of (TiO2/B2O3) were found to increase, along with the elastic moduli. The thermal stability, energy gap, and refractive index of the prepared glasses increased as the concentration of (TiO2/B2O3) was increased.

    更新日期:2019-12-20
  • Enhanced Photodegradation Activity of Organic Pollutants Contained in Sewage Through Construction of a CuO/Ag Composite Nanostructure
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-19
    Qiao Chen, DeLiang Liu, Binhua Cao, Zhijun Wang, Tinglan Wang, Boyou Wang, Ziyi Wang, Yuxiao Yang, Xiaobo Xiong, Yongqian Wang

    Noble metal deposition is one of the most effective optimization methods for improving the photochemical properties of metal semiconductor oxides. In this paper, vertically aligned CuO nanowires were synthesized by means of a facile thermal oxidation method on Cu mesh. Subsequently, Ag nanoparticles were deposited on the surface of the CuO nanowires by vacuum coating, forming a CuO/Ag composite nanostructure. The morphology, phase structure, elemental distribution, wetting properties and optical properties of the CuO/Ag composite nanostructures were characterized by field emission scanning electron microscopy, x-ray diffraction, energy dispersion spectrometry, contact angle measurement and UV–Vis spectrophotometry, respectively. We also explored the effect of the amount of Ag nanoparticle deposition on the structure and properties of CuO/Ag composite nanomaterials. The CuO/Ag composite nanostructures exhibited better photocatalytic properties and were found to effectively degrade organic pollutants in sewage, after Ag nanoparticle deposition.

    更新日期:2019-12-20
  • Current–Voltage Characterization of Transparent ITO/ZnO:B/ZnO:(Al + In)/Ag Schottky Diodes Prepared with Multilayer Films by Sol–Gel Deposition
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-19
    Manuel A. Hernández-Ochoa, Humberto Arizpe-Chávez, Rafael Ramírez-Bon, Alain Pérez-Rodríguez, Manuel Cortez-Valadez, Mario Flores-Acosta

    Abstract We fabricated a ZnO-based Schottky diode via the deposition of a ZnO film co-doped with Al + In (4 at.%) on a boron-doped ZnO film (8 at.%). Each film was prepared by layering coatings (2, 3, 4, and 5 layers) by sol–gel deposition. The finished diode consists of the combination of seven layers (each layer with a thickness of around 90 nm). The total thickness of the diode is around 700 nm. The films were previously studied and structurally, optically and electrically characterized. Additionally, for comparative purposes, we fabricated and characterized un-doped ZnO films. The energy bandgap values of the un-doped films, mono-doped films, and co-doped films were 3.30 eV, 3.32 eV, and 3.34 eV, respectively. X-ray diffraction did not show traces of different phases from hexagonal Wurtzite-type ZnO. The electrical resistivity values obtained were 386, 4.44 × 104, and 3.37 Ω-cm, respectively. The junction diodes were built by depositing layers of the high-resistivity material (ZnO:B) on ITO conductor substrates, followed by the deposition of layers of the low-resistivity material (ZnO:Al + In) on the same substrate. The I–V characteristics of these diodes were analyzed in terms of the number of the deposited layers (or the different thickness of the films). The results show a Schottky-type behavior in the dark and under light (spot lamp of 160 W), which is controlled by the thickness of the resistive layer. From the I–V curves, the characteristic parameters including barrier height, ideality factor, and series resistance were calculated. From the transconductance (gm=dI/dV), it was possible to identify the presence of all the layer–layer interfaces. Depending on the thickness of the resistive ZnO:B film, we found a region of negative differential resistance and a region of visible light detection.

    更新日期:2019-12-20
  • Investigation of Thermoelectric Properties of Ag 2 S x Se 1−x ( x = 0.0, 0.2 and 0.4)
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-18
    Saurabh Singh, Keisuke Hirata, Dogyun Byeon, Takuya Matsunaga, Omprakash Muthusamy, Swapnil Ghodke, Masahiro Adachi, Yoshiyuki Yamamoto, Masaharu Matsunami, Tsunehiro Takeuchi

    Abstract Materials best-suited for direct application exhibit a high thermoelectric figure of merit (ZT) close to unity, from room temperature to ∼ 400 K. In this work, we investigated the thermoelectric behavior of Ag2Se, and a sulfur substituted Ag2Se system, i.e. Ag2S0.2Se0.8 and Ag2S0.4Se0.6 , in the temperature range of 300 K to 500 K. With strong anharmonic lattice vibration and semiconducting electronic structure, these materials showed thermal conductivity less than 1 W m−1 K−1, electrical resistivity ∼ 1 mΩ cm, together with moderate Seebeck coefficient values of ∼ − 140 μV K−1 in the low-temperature phase. We were able to achieve ZT equal to unity in a wide temperature range of 350–400 K, with a maximum value of ZT = 1.08 at 350 K for the Ag2S0.4Se0.6 material.

    更新日期:2019-12-20
  • Optimization of Digital Growth of Thick N-Polar InGaN by MOCVD
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-17
    Shubhra S. Pasayat, Cory Lund, Yusuke Tsukada, Massimo Catalano, Luhua Wang, Moon J. Kim, Shuji Nakamura, Stacia Keller, Umesh K. Mishra

    Abstract Smooth 200 nm thick N-polar InGaN films were grown by metal–organic chemical vapor deposition (MOCVD) on sapphire using a digital approach consisting of a constant In, Ga, and N precursor flow with pulsed injection of H2 into the N2 carrier gas. Using this growth scheme, the H2 injection time was altered and the effect on the morphology and indium incorporation in the films observed. The effect of periodic insertion of additional GaN inter-layers on the surface morphology of the InGaN layers was also studied.

    更新日期:2019-12-20
  • Light Emission in Nd Doped Si-Rich HfO 2 Films Prepared by Magnetron Sputtering
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-17
    T. Torchynska, L. G. Vega Macotela, L. Khomenkova, F. Gourbilleau

    Hafnium oxide films doped with Si and Nd atoms were produced by radio-frequency magnetron sputtering of a HfO2 target topped with calibrated Si and Nd2O3 pellets in pure argon plasma followed by an annealing in nitrogen atmosphere during tA = 15 min at different temperatures (TA = 800–1100°C). The evolution of structural, chemical and luminescent properties of the films with TA was studied by means of the scanning electronic microscopy (SEM), x-ray diffraction (XRD), Raman scattering, energy dispersive x-ray spectroscopy and photoluminescence (PL) methods. The SEM method revealed that the surface of as-deposited film consists of the grains with the mean size of 20–60 nm. Annealing treatment stimulated the growing of the grains (up to 100 nm in lateral size) and film densification. The presence of Si-rich phase was detected by Raman scattering spectra in as-deposited films and those annealed at low TA. The TA increase results in the phase separation process. For the films annealed at TA > 950°C, the tetragonal HfO2 and SiO2 phases were clearly detected by the XRD method. PL spectra of the films were found to be complex. They demonstrated several PL bands in the visible (400–750 nm) and infrared (800–1430 nm) spectral ranges. Besides PL components caused by the recombination of carriers via host defects, the PL signal from Nd3+ ions due to the transition in the 4f inner electronic shell was observed. The highest Nd3+ related PL signal was observed for the films annealed at TA = 950°C. Peculiarities of PL excitation and the mechanism of the phase separation are analysed and discussed.

    更新日期:2019-12-20
  • Motorcycle Waste Heat Energy Harvesting Using Thermoelectric Generators
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-11
    Mohd Shaharil Omar, Baljit Singh, Muhammad Fairuz Remeli

    Meeting the increasing global demand for energy coupled with the depletion of fossil fuel sources has created breakthroughs in research on waste heat energy harvesting devices. By utilizing waste heat, energy consumption does not grow and is efficiently used instead. Harvesting energy from automobiles has promising outcomes for the application of thermoelectric generators (TEGs). Heavy duty diesel engines, pick-up trucks, sport bikes and model airplanes are involved in research attempting to do away with heavy batteries or alternators. For this study, a single cylinder, 100 cc Honda EX5 Dream, which is also known as ‘Kapcai’, was used to study the viability of installing TEGs for waste heat recovery in underbone of the motorcycle chassis. The natural convection passive cooling system of fin was used to dissipate heat for cold side of the TEGs to maintain temperature difference across TEGs of the motorcycle waste heat recovery system. Two currently commercially available TEG modules were used and were connected in series and parallel in order to obtain output power. Results for a single module of each of the two TEGs testing recorded a temperature gradient of 57.5 °C and 62.7 °C with open circuit voltage of 1.677 V and 1.704 V, respectively. The highest temperature difference and output voltage were recorded at 73.2 °C and 4.2 V in series arrangement for both the TEGs. In the same arrangement, the highest power output obtained was 551.0 mW. The outcomes from this field testing shows the applicability of waste heat recovery from the underbone chassis of a typical motorcycle in charging small portable devices such as smartphones or power banks for the rider of motorbike.

    更新日期:2019-12-20
  • A Highly Enhanced Photoluminescence of Eu 3+ -Activated CaTiO 3 Phosphors via Selective A-Site and B-Site Cation Substitutions (Sr 2+ and Sn 4+ )
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-18
    Xinyi Chen, Yudong Xu, Caiyue Zhao, Lei Wang, Shuyu Wen, Yulin Shi, Qing Xia, Min Shi, Yimiao Chu, Fang Li, Fan Chen, Kai Liu

    Sr2+ and Sn4+ doped CaTiO3:Eu3+ phosphors were prepared by a high temperature solid-state method. X-ray diffraction characterization shows that the sample calcined at 1200°C is pure and has an orthorhombic crystal lattice. Photoluminescence (PL) measurement shows that CaTiO3:Eu3+ has five excitation peaks at 363 nm, 381 nm, 398 nm, 418 nm, and 466 nm, respectively corresponding to the transitions 7F0 → 5D4, 7F0 → 5L7, 7F0 → 5L6, 7F0 → 5D3 and 7F0 → 5D2 of Eu3+. The main emission peaks of CaTiO3:Eu3+ at 592 nm and 613 nm are ascribed to the 5D0 → 7FJ (J = 1, 2) transitions of Eu3+. In addition, PL emissions at 592 nm and 613 nm of CaTiO3:Eu3+ phosphors are enhanced remarkably through A-site substitution of Ca2+ with Sr2+ or B-site substitution of Ti4+ with Sn4+. Noticeably, the emission intensity of Ca(Ti,Sn)O3:Eu3+ is nearly three times higher than that of CaTiO3:Eu3+. The reason is that substitution of Ti4+ with Sn4+ induces a large lattice distortion, which promotes the 5D0 → 7F2 transition probability and thus enhances the emissions at 613 nm. It is also found that Sr2+ substitution narrows the optical bandgaps of CaTiO3:Eu3+ , while Sn4+ substitution widens them. In addition, chromatic purity of the phosphors shows a remarkable dependence on the asymmetric ratio.

    更新日期:2019-12-19
  • The Design and Preparation of Transparent Hybrid Composite Thin Films with Excellent Optical Properties and Improved Thermal Insulation by Optimized Combination of Nanomaterials
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-18
    Te Hu, Yuchang Su, Ian R. Baxendale, Yaping Zhang, Jinfan Zhu

    For a single nano-optical material, it is difficult to possess high transmittance and adequately filter ultraviolet (UV) and infrared radiation (IR) simultaneously. Consequently, hybrid nano-optical materials comprising components of appropriate proportions for superimposing serviceable optical property are required. The design, optimization and processing of new composite blends with an aim to creating defect free thin films is far from a trivial endeavor. In this report, optimum composition and optical properties of hybrid nano-optical material has been determined and improved by crossover matching experiments and ball milling, respectively. Film preparation has been optimized to reduce defects expressed as cracks, tiny bubbles, strips, groove points, corrugation, and formation of acicular fibers by regulating proportion of polyvinyl butyral colloid and dry film processes. Two ameliorative processing conditions are exemplified where the resultant composite films possessed 86% maximum transmittance in the visible range and 90% and 50% blocking rate with respect to the IR and UV bands.

    更新日期:2019-12-19
  • Effect of Post-Heat Treatment on Physical Properties of Nanostructured TiO 2 Powders Prepared by a Sol–Gel Method
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-18
    H. H. Afify, Salma S. Asad, A. M. Badr, H. A. Elshaikh

    A nanostructured TiO2 powder was produced by a sol–gel method. The resultant powder was sintered at different temperatures ranging from 300°C to 800°C, for a constant time of 2 h. X-ray diffraction (XRD) results indicated that an increase in sintering temperature caused a transformation of the TiO2 powder from amorphous to polycrystalline. At temperatures lower than 500°C, a pure polycrystalline anatase phase was present, while a rutile phase was present at 800°C. A gradual transformation from the anatase to rutile phase occurred between 500°C and 800°C. A high-resolution transmission electron microscope (HRTEM) with selected area electron diffraction (SAED) capability was used to elucidate the shape and size of the particles as well as their electron diffraction. The TEM images displayed an increase in particle size from 20 nm to 90 nm when the sintering temperature was increased from 300°C to 800°C. The SAED patterns supported the XRD results. The diffuse reflectance data for the investigated samples were used to estimate their bandgap energy (\( E_{\rm{g}} \)), which revealed that samples sintered at 500°C and 800°C had energy gap values of 3.18 eV and 3.01 eV, corresponding to pure anatase and pure rutile phases, respectively. Current–voltage (I–V) measurements were carried out on the sintered samples to calculate sample resistivity at room temperature. The results showed a slight increase in conductivity with increased sintering temperature up to 700°C, followed by a significant increase at 800°C.

    更新日期:2019-12-19
  • Influence of Gamma-Irradiation on Structural, Optical and Photocatalytic Performance of TiO 2 Nanoparticles Under Controlled Atmospheres
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-17
    A. Bourezgui, I. Kacem, M. Daoudi, Ahmed F. Al-Hossainy

    The effect of gamma-rays on structural, optical and photocatalytic properties of TiO2 nanoparticles under controlled atmospheres are studied to further improve photocatalytic performance. The sol–gel TiO2 powders were deposited with spin-coating technique, annealed at 500°C then finally irradiated by gamma-rays. The structural and optical characteristics of samples were investigated by Fourier transform infrared spectroscopy, x-ray diffraction and UV-visible spectroscopy (UV). The time-dependent density functional theory (TD-DFT) calculation are used to determine ground geometries and electronic structures of TiO2 nanostructures. DFT calculations present an excellent conformity with experimental results, and a high anisotropy in stretched thermal and electrical conductivity TiO2 nanostructures was found. Structural and optical results show that gamma radiation did not change the crystallinity of TiO2 nanostructures and leads to an optical band gap reduction to 3.039 eV. The gamma radiation effect on photocatalytic performance was investigated by methylene blue degradation as a typical pollutant. Gamma radiation has been discovered to improve considerably the degradation of pollutants compared with unirradiated TiO2.

    更新日期:2019-12-18
  • Electrochemical Performance of Nanocrystalline Vanadium Pentoxide Thin Films Grown by RF Magnetron Sputtering
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-17
    M. Dhananjaya, N. Guru Prakash, A. Lakshmi Narayana, O. M. Hussain

    Nanocrystalline V2O5 thin films were prepared by radio frequency (RF) magnetron sputtering and explored as potential electrodes for Li-ion microbatteries and supercapacitors based on microstructure and electrochemical properties. All the films grown in the substrate temperature (Ts) range 250–350°C exhibited predominant (001) orientation corresponding to the orthorhombic V2O5 layered structure. However, notable changes were observed in the surface morphology and crystallite size of the grown films by varying the substrate temperature. The films deposited at Ts of 250°C showed uniformly distributed spherical grain morphology and demonstrated pseudocapacitive behavior with a specific capacitance of 960 mF cm−2 at current density of 1 mA cm−2 with good cycle stability. The films deposited at Ts of 350°C showed needle like nanorod structure with an average crystallite size of 36 nm. These films exhibited sharp oxidation and reduction peaks, exhibiting cathodic behavior with a discharge capacity of 62.6 μAh cm−2 μm−1 at a current rate of 50 μA.

    更新日期:2019-12-18
  • Linear and Non-linear Optical Parameters of Diluted Magnetic Semiconductor CdS 0.9 Mn 0.1 Thin Film: Influence of the Film Thickness
    J. Electron. Mater. (IF 1.676) Pub Date : 2019-12-17
    A. M. Abdelraheem, M. I. Abd-Elrahman, Mansour Mohamed, N. M. A. Hadia, E. R. Shaaban

    The optical properties of CdS0.9Mn0.1 thin film with different thicknesses (d = 300, 450, 600, 750, 900 and 1000 nm) were explored. The Swanepoel method was employed to calculate the thickness of the studied films. Analyses of the absorption spectra indicated the existence of allowed indirect and direct transition mechanism in the CdS0.9Mn0.1 thin films. Both the absorption coefficient and optical band gap decreased while Urbach energy increased as the film thickness increased. The Wimple–DiDomenico single oscillator model was used to describe the dispersion of the refractive index. The film thickness dependence of the dispersion parameters was studied. The optical dielectric constants, optical conductivity, electrical susceptibility, and non-liner optical parameters such as the refractive index, first-order susceptibility (\( \chi^{(1)} \)) and third-order susceptibility (\( \chi^{(3)} \)) were determined. The present results show that the film thickness is an important factor which affected the optical parameters.

    更新日期:2019-12-18
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