Increasing the thickness of the SiO 2 dielectric layer used to electrically isolate AlGaN/GaN high-electron-mobility transistors led to a gradual increase in the sheet carrier density of the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface. An increase of approximately 33% in sheet carrier density was observed after depositing 125 nm of SiO 2 by plasma-enhanced chemical vapor deposition

In this study, we present the design, the modeling, the fabrication, and the characterization of ring–dot type piezoelectric thin-film transformers (PTFTs). The structure of the PTFTs was a simple circular plate of Pb(Zr,Ti)O 3 (PZT) thin film on a Si layer with ring–dot top electrodes and it was suspended by four pantograph-shaped bridges. We estimated the performance of the PTFTs by finite-element

We adjusted the B site excess ratio and the quantity of additional Bi 2 O 3 in the KNN calcined powder in order to establish a process to fabricate, (K,Na)NbO 3 (KNN)-based single crystals, with large and uniform configurations and relatively stable low porosity, using the seed-free solid-state crystal growth method. When the activity of abnormal grain growth during sample heating was controlled appropriately

For a comprehensive study of the growth mechanisms of Pb(Zr,Ti)O 3 (PZT), we employed a combinatorial sputtering method that enabled us to fabricate films with composition and substrate temperature gradients in-plane. The gradient of the amount of Pb supply was created using PZT ceramic and Pb 3 O 4 powder targets. The substrate temperature gradient was generated in an orthogonal direction by inserting

Multilayer tin oxide/gold/tin oxide (SnO 2 /Au/SnO 2 ) was deposited by atomic layer deposition and an e-beam evaporator. The structural, electrical, and optical properties of the SnO 2 /Au/SnO 2 multilayer were investigated. Au formed islands at a thickness less than 3 nm. As the Au interlayer thickness increased, the Au islands merged, resulting in a continuous film 12 nm thick. As the Au interlayer

We have designed and fabricated a compact, 250 cm 3 electric field cooling alternate current poling (FC ACP) system and obtained an enhanced dielectric permittivity ( ε T 33 / ε 0 ) of 7920 which was 10 to 33% larger than that of high temperature (HT) ACP of 0.70Pb(Mg 1/3 Nb 2/3 )O 3 -0.30PbTiO 3 (PMNT) single crystal (SC) with phase change temperature ( T pc ) of 93 °C. However, when the FC ACP temperature

We demonstrated high free dielectric permittivity ( ε 33 T / ε 0 ) > 8000 and piezoelectric coefficient d 33 > 1950 pC/N of 72Pb(Mg 1/3 Nb 2/3 )O 3 -28PbTiO 3 (PMN–28PT) single crystals (SCs) obtained by low-voltage AC poling (LV ACP) of 1.5 to 3.5 kV RMS cm −1 at a high temperature (HT) of 80 °C in an air atmosphere. The minimum standard deviation ( σ ) of 170 was similar to conventional DC poling

Adjusting compositions of two barriers forming a (111)-oriented InGaAs/AlGaAsSb quantum well (QW) is proposed as a method to eliminate the effective magnetic field due to the Rashba and linear-in-momentum Dresselhaus spin–orbit interactions in the zeroth and first orders in the gate electric field. The resulting suppressed Dyakonov–Perel spin relaxation is used to achieve a high on/off ratio of the

We investigate the effect of silicon nitride (SiN x ) films in n-type front-emitter (n-FE) crystalline Si (c-Si) solar cells on the potential-induced degradation (PID) of n-FE photovoltaic (PV) modules. A negative-bias PID test for a few min does not degrade the performance of PV modules with n-FE cells without SiN x /Si dioxide (SiO 2 ) stacks, unlike in the case of PV modules with cells with SiN

We report on the anomalous excitation-power dependence of the band-edge emission in Si after 2 MeV electron irradiation. It is well-established that the dependence of the emission intensity I on the excitation power L is generally follows the power law, I ∝ L n with the exponent n between 1 and 2. However, the exponent n increases after the electron irradiation and becomes larger than 2 at temperatures

The migration behavior of a material encapsulated in a carbon nanotetrahedron/ribbon structure was observed in situ using a scanning electron microscope equipped with a microprobe. Observations suggest that the encapsulated material was expelled through the nanotetrahedron/ribbon structure and partially filled the nanotetrahedron when an unbiased probe was positioned at an open end of the nanostructure

This paper presents preliminary results for a new design of a pulsed linear plasma device that generates electromagnetic plasma propulsion. The current sheath dynamics and the plasma propulsion along an extension tube have been studied. Breakdown of helium gas occurs between coaxial electrodes when applying a high-voltage pulse. This paper presents measurements with a number of probes, as well as camera

Soft errors are widely recognized as a reliability issue, and are a circuit malfunction caused by particle radiation. Identifying soft-error sensitive volumes of a semiconductor circuit is useful for evaluating soft-error sensitivity and developing countermeasures against soft errors. This paper quantifies the spatial resolution of soft-error sensitive-volume analysis by scanning two-photon absorption

We investigated the FM noise characteristics of a distributed feedback laser under optical negative feedback from a Fabry–Perot optical filter using delayed self-homodyne coherent detection with a high-frequency range of 1 × 10 5 –2 × 10 10 Hz. The measured FM noise power spectral densities of the laser under the optical negative feedback strongly depend on the modulation responses of the laser. These

An aluminum oxide (Al 2 O 3 ) passivation film that prevents the oxidation of a sputtered and sulfurized molybdenum disulfide (MoS 2 ) film was investigated for an enhancement of the Hall-effect mobility. A remarkably high Hall-effect electron mobility value of 100 cm 2 V −1 s −1 was achieved using 3 nm passivation film, as compared to 25 cm 2 V −1 s −1 for an as-deposited MoS 2 film, because sulfurization

Negligible threshold-voltage shift is reported for oxide thin-film transistors (TFTs) under high current(3 μ A) and tensile bending stress (2 mm radius). The good stability is attributed to a circular TFT structure with electrically shorted top and bottom gates, and a polyimide substrate embedded with carbon-nanotubes for mechanical support and damage-free detachment from carrier glass. The circular

The Langmuir limit, defined by B. D. Langmuir, was derived from Lambert’s law. For convex cathode or curved trajectories, beams with brightness higher than the Langmuir limit are obtainable. Measured brightness varies dramatically when we vary the excitation in the first lens of a system consisting of an electron gun and two magnetic lenses. The ratios of maximum to minimum brightness were measured

Controllability of the nanostructures in spinel-type manganese oxide ZnMnGaO 4 by changing cooling rate was studied via transmission electron microscopy (with selected area electron diffraction and bright- and dark-field imaging) as well as X-ray diffraction. The Quench sample exhibited a tweed pattern, suggesting the coexistence of two phases at the nanometer scale. The nanostructural changes from

We investigated the structural and magneto-transport properties of Fe/SrO/MgO/Fe magnetic tunnel junctions (MTJs), in which SrO has a large lattice mismatch (Δ a / a ∼ 21%) with Fe. Despite such a large Δ a / a , structural analyses revealed that a fully epitaxial Fe(001)/SrO(001)/MgO(001)/Fe(001) structure was successfully formed. We observed high magnetoresistance (MR) ratios up to 98% at 20 K (65%

A linewidth reduction of a distributed feedback quantum cascade laser (DFB-QCL) based on optical feedback for a mid-infrared (MIR) cavity ring down spectroscopy (CRDS) 14 C spectrometer is presented. A cat-eye reflector as well as a path-length enhancement by a Herriott cell were employed for a compact optical setup. The laser linewidth was evaluated by monitoring the beat frequency between the DFB-QCL

We report on the generation of two-dimensional hole gas (2DHG) with robust stability at the interface of c-BN/diamond upon proper interface engineering without the requirement of hydrogen on diamond. The areal density of the 2DHG is as high as 9.85 × 10 12 cm −2 , and the hole mobility is as high as 924 cm 2 V −1 s −1 . The intrinsic electron-deficiency nature of the interfacial carbon–boron bonds

In an application for metallization contact of Ag thick-film conductor onto the SiN x -coated Si wafer for solar cells, we examined the wettability, reactivity, microstructure, and electrical contact of two kinds of glass frits: lead borosilicate and lead tellurite. The lead tellurite frit exhibited superior wettability on Si and higher reactivity with SiN x and formed the thinner glass layer between

The Compton camera technique is a well-known method of visualizing the distribution of radiation sources that emit gamma rays with energies of approximately 1 MeV. One major disadvantage of this technique is that the reconstructed image is degraded owing to the appearance of artificial uneven structures caused by accumulating rings estimated from each event. In this study, we demonstrated that we can

Visible multi-color electrochromism has been achieved by mixing two colors at one working electrode using a hetero-multilayer layer-by-layer (LbL) film. The hetero-multilayer LbL film consists of a redox-conductive layer-by-layer (LbL) film (inner layer) and an electrochromic LbL film (outer layer). The redox-conductive film was constructed by LbL deposition of a cationic copolymer that contains ruthenium

3D integral imaging (II) has been deemed as a promising technology for a future market in the fields of entertainment and communications. However, the limited depth of field (DOF) hinders the wide application of II technology. In this study, we propose a marginal DOF model and a computation method of optimal viewing resolution, which considers the human visual system (HVS). Firstly, we analyze the

Thin-film electroluminescent devices composed of an (In 0.975 Sn 0.025 ) 2 O 3 anode, a phosphor, and a Sn 0.95 Sb 0.05 O 2 cathode were prepared by a sol–gel and firing method. The phosphor thin films were composed of four layers, (Ca 0.6 Sr 0.4 ) 0.998 Pr 0.002 Ti 0.9 Al 0.1 O 3– δ or Ca 0.6 Sr 0.4 Ti 0.9 Al 0.1 O 3– δ . The relation between the space distribution of Pr 3+ ions and the electric/electroluminescence

Synchrotron radiation X-ray powder diffraction has visualized the charge order of Bi 3+ and Bi 5+ ions and the nature of chemical bonds in BaBiO 3 in electron charge density distribution maps. The Bi 3+ –O bond is considerably more ionic than the Bi 5+ –O bond in all four phases. BaBiO 3 can be regarded as an ionic crystal in the prototype structure comprising isolated Ba 2+ and Bi 3+ ions as well

Accurate differentiation of whether the defect position is located on the inside or outside surface is necessary in the low-frequency electromagnetic detection technique (LFET) on oil and gas pipelines. We design a set of composite probe arrays that consisted of inductive magnetic coils (LFET coils) and eddy current testing (ECT) coils to accomplish comprehensive inspection, meanwhile, the theoretical

To clarify a guideline for designing a vibration energy harvesting device using magnetostrictive materials, the characteristics of the vibration energy harvesting device with an Fe–Ga alloy single crystal were investigated. Magnetic flux density changes and strain amplitude generated in the device were measured using coils and strain gauges, respectively. The results were compared between devices with

The dislocation structure around the Vickers indentation on a hydride vapor-phase epitaxy GaN wafer was observed by multi-photon photoluminescence imaging and cross-sectional scanning transmission electron microscopy. Straight dislocation lines parallel to the six equivalent ##IMG## [http://ej.iop.org/images/1347-4065/59/9/091005/jjapabb00cieqn3.gif] {$\left\langle 11\overline{2}0\right\rangle $} directions

The molecular orientation of dinaphtho[2,3- b :2′,3′- f ]thieno[3,2- b ]thiophene (DNTT) thin films on modified silicon dioxide (SiO 2 ) and copper oxide (CuO x ) substrates whose surfaces were treated by 6-[(3-trisilanol)propylamino]-1,3,5-triazine-2,4-bis(2-aminoethylamine) (TAS) was investigated using near-edge X-ray absorption fine structure and ultraviolet/X-ray photoelectron spectroscopy. The

The monolayer crystal phase structure of the organic semiconductor 7-decyl-2-phenyl[1]benzothieno[3,2- b ][1]benzothiophene was reinvestigated. A smaller two- or three-step bilayer–monolayer transition model than the previous transition model was newly proposed. The carrier mobilities of the resultant two monolayer crystal structure models were theoretically compared. The results show that the antiparallel

The final goal of this study is to provide a sleep-monitoring device that indexes sleep status and allows users to measure their sleep status and easily recognize how to improve their sleep. As a first step toward achieving this, we have developed a prototype system with a simple structure consisting of a bed sheet and a pillow case embraided with a piezoelectric poly-L-lactic acid (PLLA) braided cord

The composition dependencies of crystal structure, and electrical and electromechanical properties were systematically investigated for epitaxial films of (1− x )(Bi 0.5 Na 0.5 )TiO 3 – x (Bi 0.5 K 0.5 )TiO 3 [(1− x )BNT– x BKT ( x = 0 –1)] deposited on (100) c SrRuO 3 //(100)SrTiO 3 substrates by a hydrothermal method. An In-plane crystal lattice was clamped by that of underlying SrRuO 3 irrespective

(Li,Na,K)NbO 3 -based multilayered piezoceramics were characterized by performing unipolar polarization electric field measurements and impedance spectroscopy. Subjecting an as-poled sample to up to 10 7 cycles in an applied 4 kV mm −1 unipolar cyclic field at 100 °C reduced its polarization by 8.9%. The impedance spectra of as-sintered, as-poled, and fatigued samples were acquired and analyzed. Two

Crystallography and dielectric properties in Dion–Jacobson layered perovskites, CsNdNb 2 O 7 and RbNdNb 2 O 7 , have been examined in dense polycrystalline samples, and polarization hysteresis loops that substantiate ferroelectricity have been observed at room temperature. The theoretical mechanism for the spontaneous polarization, “hybrid improper ferroelectric mechanism,” induced by a combination

The deposition behavior of copper particles during the aerosol deposition (AD) process was predicted according to the particle velocity via a numerical model. Plastic deformation of Cu particles was predicted by a cumulative effect among the injected carrier gas consumption, particle velocity, internal energy, compressive strain, and heat-induced thermal softening of the particle. Besides, there is

Competing dynamics was analyzed for generation, recovery and accumulation of ion irradiation damage using three methods including He-ion channeling backscattering. The in situ tracing of electrical conductance after pulsed 100 keV proton irradiations at 23 °C–92 °C revealed that the subsequent recovery process was a second-order reaction with an activation energy of 0.74 eV in n -type and 0.31 eV in

The bandgap energy of InGaN alloy materials can be controlled by changing their alloy composition. Since the compositional fluctuation in the InGaN quantum wells (QWs) greatly affects the characteristics of optical devices, it is very important to understand the electronic structures of such fluctuated InGaN-QW systems for the improvement of their device characteristics. Mobility edge (ME), which is

We examined the effect of the discharge tube temperature on the densities of ##IMG## [http://ej.iop.org/images/1347-4065/59/9/098002/jjapabaebdieqn3.gif] {${{\rm{N}}}_{2}({A}^{3}{{\rm{\Sigma }}}_{u}^{+})$} and ##IMG## [http://ej.iop.org/images/1347-4065/59/9/098002/jjapabaebdieqn4.gif] {${\rm{N}}{(}^{4}{S}^{{\rm{o}}})$} in microwave-excited remote nitrogen plasma. The density of ##IMG## [http://ej

We have newly developed mist CVD-derived Hf 1− x Zr x O 2 films and investigated their physical properties and basic electrical properties for application to ferroelectric analog memory device such as synaptic device for neuromorphic system. It is observed that the films consisted of microcrystal grain including ferroelectric orthorhombic phase by AFM and GIXRD measurements. Both HfO 2 and ZrO 2 film

Our aim is to broaden the dynamic range of target DNA detection by an Au nanoparticle (AuNP) sandwich assay based on complementary DNA hybridization. We conducted electrophoresis band analysis for different sizes and concentrations of AuNPs bearing different numbers of surface-conjugated probe DNA molecules. We found that the AuNP concentration is critical to determining the maximum quantification

This study investigated the electromechanical properties of MEMS piezoelectric vibration energy harvesters (MEMs-pVEHs) under various impulsive forces to discuss effective harvesting energy from random vibrations. MEMS-pVEHs with different resonance frequencies with an energy conversion efficiency close to the theoretical maximum were used. The output waveforms for various impulsive force could be

The modulus spectra of organic field-effect transistors (OFETs) with electrode overlap and peripheral regions have been experimentally and theoretically investigated. The complex impedance of regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) OFETs with electrode overlap and peripheral regions was measured with a frequency response analyzer. The complex modulus was derived from an equivalent circuit

Hollow-core screw dislocations along [0001] in hexagonal silicon carbide single crystals, i.e. micropipes, are known to heal or close during annealing or epitaxial growth procedures. Although the healing and closing are understood to be caused by the dissociation of hollow-core superscrew dislocations into multiple closed-core elementary screw dislocations with Burgers vector of 1 c , the transformation

Voronkov developed a theory on the grown-in defects in Si crystals. One of the most important properties deduced from the theory is the critical value of v/G , ( v/G ) crit , where high-quality crystals can be grown. According to Voronkov’s explanation on the concentration gradients, we proposed a simple expression of ( v/G ) crit , which is proportional to the concentration gradient. We examined pair

Undoped and Ce-doped CaLaAl 3 O 7 crystals were synthesized by the optical floating zone method and photoluminescence and scintillation properties were evaluated. A broad peak at 420 nm due to the 5d-4f transitions of Ce 3+ is observed from the Ce-doped samples based on the measurement of photoluminescence and scintillation spectra. The photoluminescence and scintillation decay time constants attributable

We successfully improved quality of tin oxide (SnO 2 ) films formed on m -plane sapphire substrates by mist chemical vapor deposition. The crystal quality was characterized mainly by the FWHM of the X-ray diffraction ω -rocking curve. We found that the use of tin acetate [Sn(CH 3 COO) 4 ] solution led to the formation of high-quality SnO 2 film, where FWHM was as narrow as 0.1°. Using tin chloride

Simultaneous measurement of atmospheric moisture and temperature in the presence of airborne particulates over an extended region using a single sensor is very important for the prediction of fog in an open environment. Here, we have developed an ultrasonic technique to measure relative humidity and temperature of open-air containing suspended particulate matter in a controlled environment. We achieved

The populations and propagation behaviors of pure and mixed threading screw dislocations (TSDs) in physical vapor transport (PVT) grown 4H-SiC crystals were investigated using X-ray topography. The X-ray topography studies revealed that mixed TSDs, which have a Burgers vector component within the basal plane in addition to the c -component, were dominant in PVT-grown 4H-SiC crystals, even though they

We investigated the spin-anomalous Hall effect (SAHE) in ferromagnetic Fe–Co binary alloys with different compositions. The ferromagnetic resonance (FMR) measurement in Fe 1− x Co x /Ti/Py trilayer structures was performed to detect the SAHE in Fe 1− x Co x . The modulation of FMR linewidth in the Py layer due to the SAHE was observed. The effective spin-anomalous Hall angle changed from a positive

Kelvin probe force microscopy (KPFM) is a useful technique for simultaneously visualizing topography and contact potential difference (CPD). Although frequency-modulation (FM) KPFM has high spatial resolution and sensitivity, it is not readily applicable to measuring large protrusions owing to the instability of the feedback condition. Here we investigate the combined use of amplitude-modulation and

The characteristics of a MOS diode with Mg-ion-implanted GaN before activation annealing were investigated. Mg ion implantation onto n-GaN with slightly high Si doping concentration (5 × 10 17 cm –3 ) was performed with a moderate dosage (1.5 × 10 12 cm –2 ). The completed MOS diode showed n-type features. The capacitance–voltage ( C–V ) and capacitance–frequency ( C–f ) characteristics of the MOS

Inclusion of a large amount of deep eutectic solvent (DES) in a microemulsion (ME) may enhance transdermal permeation of resveratrol (RSV) due to its high solubility in DES of the inner phase. We prepared MEs with different DES loading and surfactant composition, and investigated the entrapment amount of RSV, the structures of the MEs, and their skin penetration amount. We found that MEs at Tween-80/Span-20 = 4/1

We report on a new type of high-power, single-mode vertical-cavity surface-emitting laser (VCSEL) based on the lasing of a slow-light mode laterally propagating in a long-apertured VCSEL structure. A VCSEL length of 500 μ m produces high single-mode power with narrow beam divergence for sensing and 3D imaging applications. Slow-light modes show a lower threshold current and better beam quality. We

In thermal atomic layer etching (ALE) of Ni, a thin oxidized Ni layer is removed by a hexafluoroacetylacetone (hfacH) etchant gas at an elevated surface temperature, and etching ceases when a metallic Ni surface appears (self-limiting step). However, atomistic details of the self-limiting step was not well understood. With periodic density-functional-theory calculations, it is found that hfacH molecules

We theoretically report the generation of a frequency-doubling Bessel-like beam in a nonlinear electro-optic photonic crystal. For nonlinear beam shaping in a sample, the entire crystal is equivalent to a series of positive and negative micro-axicons in tandem in the interactions where duty cycle is of great importance. Despite the inevitable domain deviations introduced by the poling, it has little

We present an optical modeling and characterization study of prototype ultraviolet laser diode (LD) structures grown on single-crystal AlN substrates, with focus on the reduction of modal loss caused by optical mode coupling to the absorptive layers on the p-side (i.e. p-contact and p-metal layers). The transparent AlN substrates enabled optical pumping for measuring modal loss without requiring functioning

We fabricated polyvinyl chloride (PVC) films containing leuco crystal violet (LCV) to develop a radiochromic material with high sensitivity to radiation. For comparison, polyvinyl butyral, polystyrene, and poly(methyl methacrylate) films containing LCV were additionally prepared. The absorption spectra of these films before and after X-ray irradiation were measured. The change in the absorbance of

Efficient terahertz (THz)-wave generation via difference frequency generation (DFG) in a GaAs-based two-dimensional photonic crystal waveguide (PhC-WG) was proposed and investigated through numerical simulations. A PhC-WG with a low-group-velocity and low-dispersion mode (LVLD PhC-WG) was designed, and THz–DFG spanning sub- to several THz in frequency was obtained. Electric field enhancement and phase-matching