-
A Watt-level noise-like Tm-doped fiber oscillator by nonlinear polarization rotation Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-11 Jingcheng Shang, Jianshu Feng, Tao Li, Tianli Feng, Yizhou Liu, Shengzhi Zhao, Yuefeng Zhao and Yuzhi Song
We propose a high-power, noise-like pulse (NLP), Tm-doped fiber oscillator applying the nonlinear polarization rotation method. The repetition rate is 12.94 MHz resulting in a pulse energy of 75.7 nJ. The emitted mode-locking spectrum can be tuned from 1885 nm to 1949 nm in a 64 nm spectral range. A theoretical model is built to illustrate the NLP dynamics and its boundary conditions with a soliton
-
Emission wavelength control of InAs/GaAs quantum dots using an As 2 source for near-infrared broadband light source applications Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-11 Nobuhiko Ozaki, Yuma Hayashi, Shunsuke Ohkouchi, Hirotaka Ohsato, Eiichiro Watanabe, Naoki Ikeda, Yoshimasa Sugimoto and Richard A. Hogg
Herein, we report an emission wavelength control technique for self-assembled InAs quantum dots (QDs) grown via molecular beam epitaxy using an As 2 source (As 2 -QDs). The As 2 -QDs exhibited photoluminescence with a shorter center wavelength and larger bandwidth than those of the QDs grown using an As 4 source. In addition, the emission center wavelength could be controlled by adjusting the time
-
Terahertz emission in an InGaAs-based dual-grating-gate high-electron-mobility transistor plasmonic photomixer Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-11 Tomotaka Hosotani, Akira Satou and Taiichi Otsuji
We report on terahertz (THz) emission from an InGaAs-based DC-current-driven dual-grating-gate high-electron-mobility transistor excited by photomixed dual continuous-wave-infrared (dual-CW-IR) laser irradiation. The difference frequency ( δf ) of the dual-CW-IR laser beams was set around the THz plasmon mode frequencies at different bias conditions. The radiation spectra from the device observed at
-
Real-time optical-resolution photoacoustic endoscope Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-07 Hui Sun, Wei Wang, Zixin Zhang, Li Wang, Wuyu Zhang, Kedi Xiong and Sihua Yang
Currently, the reported endoscopic system cannot meet the necessary conditions for real-time and optical-resolution clinical application simultaneously. In this study, by utilizing a high-repetition-rate laser and optimizing the overall structure of the probe, a real-time optical-resolution photoacoustic endoscope was developed, which could image targets in real time while maintaining a relatively
-
Understanding the influence of contact resistances on short-channel high-mobility organic transistors in linear and saturation regimes Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Shion Tazuhara, Takashi Nagase, Takashi Kobayashi, Yuichi Sadamitsu and Hiroyoshi Naito
Solution-processed organic field-effect transistors (OFETs) based on 2,7-didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C 12 -BTBT) exhibit a high channel field-effect mobilities ( μ FET ) of 10 cm 2 V −1 s −1 , while effective μ FET significantly decreases with reducing channel length. Here, we investigate the influence of contact resistances on the effective μ FET of short-channel C 12 -BTBT FETs
-
Crystallization from glacial acetic acid melt via laser ablation Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Hozumi Takahashi, Teruki Sugiyama, Seiichiro Nakabayashi and Hiroshi Y. Yoshikawa
In this work, laser ablation-induced crystallization of a single-component system was demonstrated using a melt of glacial acetic acid. We systematically investigated the dependence of the crystallization probability on laser energy, pulse duration, and beam profile. We also monitored other laser ablation-induced phenomena, cavitation bubble generation, and temperature elevation, which also depend
-
Demystifying the role of channel region in two-dimensional transistors Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Ankur Nipane, James T. Teherani and Akiko Ueda
Back-gated field-effect transistor (BGFET) structures are the most prominently used device platform to study the electrical properties of two-dimensional materials. These devices are widely modeled as Schottky barrier (SB)-MOSFETs assuming that the current flow is limited by the source-contact in the OFF state, while the channel limits the current in the ON state. Here, using an analytical model and
-
Quasi-vertical GaN-on-Si reverse blocking power MOSFETs Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Riyaz Abdul Khadar, Alessandro Floriduz, Chao Liu, Reza Soleimanzadeh and Elison Matioli
We demonstrate quasi-vertical reverse blocking (RB) MOSFETs on 6.7 μ m thick GaN grown on a 6 inch Si substrate by metalorganic chemical vapor deposition. The RB capability was achieved by replacing the ohmic drain with a quasi-vertical Schottky drain, resulting in a RB voltage of ∼300 V while preserving the ON-resistance ( R on,sp ). Schottky contacts on etched i-GaN surface were realized through
-
Visualization of water concentration distribution in human skin by ultra-multiplex coherent anti-Stokes Raman scattering (CARS) microscopy Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Daiki Kaneta, Masahiro Kimura, Philippe Leproux, Vincent Couderc, Makiko Goto, Mariko Egawa and Hideaki Kano
Ultra-multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopic imaging was used to visualize the distribution of water concentration in human skin ex vivo. The CARS signal of the OH stretching vibrational mode of water was found to coexist with the signal of intercellular lipids such as ceramides, which were visualized by a sharp vibrational band at 2882 cm −1 . Depth-resolved CARS spectroscopic
-
Broadband flux-pumped Josephson parametric amplifier with an on-chip coplanar waveguide impedance transformer Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Peng Duan, Zhilong Jia, Chi Zhang, Lei Du, Haoran Tao, Xinxin Yang, Liangliang Guo, Yong Chen, Haifeng Zhang, Zhihao Peng, Weicheng Kong, Hai-Ou Li, Gang Cao and Guo-Ping Guo
The rapid progress towards scalable quantum processors demands amplifiers with large bandwidths and high saturation powers. For this purpose, we present a broadband flux-pumped Josephson parametric amplifier integrated with an on-chip coplanar waveguide impedance transformer. Our device can be fabricated with simple and straightforward photo-lithography. This device experimentally achieves an operational
-
Enhanced electroluminescence from Ge-on-Si by precise in-situ doping and post-annealing Appl. Phys. Express (IF 3.086) Pub Date : 2021-04-06 Kodai Yamada, Youya Wagatsuma, Kazuya Okada, Yusuke Hoshi and Kentarou Sawano
We obtain strong room-temperature electroluminescence (EL) from a Ge epitaxially grown on a Si. The epitaxial Ge is in situ doped with Boron and Phosphorous by low-temperature growth, allowing for precisely controlled p-i-n structures. Also Phosphorus delta-doping is performed at the surface, resulting in low-resistivity Ohmic contacts. Vertical-type mesa-defined diodes are fabricated and an excellent
-
Real-time observation of Q-switched mode-locking in a tin selenide modulated ultrafast fiber laser Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-30 Zhenwu He, Chunxiang Zhang, Zhenhong Wang, Yu Chen, Jun Liu and Dianyuan Fan
We build a compact ultrafast Er-doped fiber laser based on the tin selenide (SnSe) saturable absorber (SA). Stable continuous-wave and Q-switched mode-locking operation states are realized. By utilizing the time-stretch dispersive Fourier transform, we explore the distinct evolution process of the Q-switched mode-locking operation in a SnSe SA modulated ultrafast Er-doped fiber laser from a real-time
-
Observation of high carrier mobility in CH 3 NH 3 PbBr 3 single crystals by AC photo-Hall measurements Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-30 Takumi Kimura, Kouhei Matsumori, Kenichi Oto, Yoshihiko Kanemitsu and Yasuhiro Yamada
Carrier mobility is one of the most fundamental material parameters of semiconductors and requisite for device applications and interpretation of physical phenomena. We determined the electron and hole mobilities of a CH 3 NH 3 PbBr 3 single crystal in the high-carrier density regime by combining AC Hall measurements under photoexcitation and two-carrier analysis. Both electron and hole mobilities
-
Spin Hall effect in amorphous YPt alloy Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-30 Takanori Shirokura, Kou Fujiwara and Pham Nam Hai
We investigated the spin Hall effect (SHE) in amorphous YPt alloy. In amorphous YPt thin films with various resistivity and thickness, we observed strong sensitivity of the effective spin Hall angle to resistivity, which was found to be governed by the intrinsic mechanism with large intrinsic spin Hall conductivity of 700 ± 100 Ω −1 cm −1 and the extrinsic side-jump mechanism with opposite polarity
-
Efficient terahertz wave generation of diabolo-shaped Fe/Pt spintronic antennas driven by a 780 nm pump beam Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-26 Miezel Talara, Dmitry S. Bulgarevich, Chiyaka Tachioka, Valynn Katrine Mag-usara, Joselito Muldera, Takashi Furuya, Hideaki Kitahara, Mary Clare Escaño, Qixin Guo, Makoto Nakajima, Garik Torosyan, René Beigang, Makoto Watanabe and Masahiko Tani
We report on efficient terahertz (THz) wave generation of Fe/Pt diabolo-shaped spintronic antennas with different Pt thicknesses fabricated on MgO substrates. Compared with the antenna-free spintronic bilayer, ∼45% and ∼98% emission amplitude improvements were obtained when using the antennas with thin and thick Pt, respectively, as THz radiation sources. The improvement can be attributed to the enhanced
-
Realizing forming-free characteristic by doping Ag into HfO 2 -based RRAM Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-26 Chung-Wei Wu, Chun-Chu Lin, Po-Hsun Chen, Ting-Chang Chang, Kuan-Ju Zhou, Wen-Chung Chen, Yung-Fang Tan, Yu-Hsuan Yeh, Sheng-Yao Chou, Hui-Chun Huang, Tsung-Ming Tsai and Simon M. Sze
In this work, Ag-doped HfO 2 -based resistive random access memory (RRAM) with high on-off ratio, low-power consumption and forming-free properties was investigated. We propose the fabrication flow of the RRAM with via-hole structure. After doping Ag into HfO 2 as the switching layer, the devices could execute resistive switching without a high-voltage forming process. The conduction mechanism was
-
Metallic nanovoid and nano hemisphere structures fabricated via simple methods to control localized surface plasmon resonances in UV and near IR wavelength regions Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-25 Kohei Shimanoe, Soshi Endo, Tetsuya Matsuyama, Kenji Wada and Koichi Okamoto
We introduce metal nanovoid (NV) and metal on metal nano-hemisphere (MoNH) structures to tune the localized surface plasmon resonance (LSPR) for wider wavelength ranges. The NV structures were constructed with metal layers on gallium oxide nano hemisphere (NH) structures, and the MoNH structures were constructed with dielectric layers and metal layers on random silver NH structures. These NH structures
-
Enhanced performance of solution-processable floating-gate organic phototransistor memory for organic image sensor applications Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-25 Hayato Abe, Reitaro Hattori, Takashi Nagase, Miho Higashinakaya, Shion Tazuhara, Fumiya Shiono, Takashi Kobayashi and Hiroyoshi Naito
This paper reports on the memory characteristics of solution-processed organic phototransistors (OPTs) based on poly(3-hexylthiophene) with organic semiconductor floating gates and their application to image sensors. The addition of a small amount of soluble fullerene to the floating-gate layer enhances the erasing characteristics, which helps increase the on- and off-current ratio of the OPT memories
-
High-pressure effects on La(O,F)BiS 2 single crystal using diamond anvil cell with dual-probe diamond electrodes Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-25 Sayaka Yamamoto, Ryo Matsumoto, Shintaro Adachi and Yoshihiko Takano
The high-pressure phase of La(O,F)BiS 2 exhibits the highest transition temperature among all the BiS 2 -based superconductors. Various studies, such as the investigation of isotope effects, have been conducted to explain its superconducting mechanism. However, there are very few reports on the electrical transport properties and vibration modes of single-crystalline La(O,F)BiS 2 under high pressure
-
The promising thermoelectric performance of newly synthesized bulk SrCu 2 GeSe 4 and BaCu 2 SnSe 4 associated with superior band degeneracy Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-23 Cong Wang and Guangqian Ding
The thermoelectric transport properties with the variations of carrier concentration, temperature and strain of bulk SrCu 2 GeSe 4 and BaCu 2 SnSe 4 are studied by using the first-principles calculations with the Boltzmann transport equation. A multi-valley degenerate valence band is gained for BaCu 2 SnSe 4 , which is responsible for its comparatively high power factor. The power factor of p -type
-
Bayesian estimation of equivalent circuit parameters of photovoltaic cells Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-23 Kazuya Tada
The equivalent circuit model of a photovoltaic cell is useful for understanding device loss mechanisms as well as the design and analysis of systems using photovoltaic cells. Although nonlinear least-squares methods are routinely applied for the extraction of equivalent circuit parameters using current–voltage characteristic curves, they only yield a point estimation sensitive to the initial value
-
Thermal stability of ferroelectricity in hafnium–zirconium dioxide films deposited by sputtering and chemical solution deposition for oxide-channel ferroelectric-gate transistor applications Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-19 Mohit, Shinji Migita, Hiroyuki Ota, Yukinori Morita, Eisuke Tokumitsu
Stability of ferroelectricity in hafnium–zirconium oxide (HZO) films deposited by sputtering and chemical solution deposition (CSD) has been investigated. After confirming the ferroelectricity of both sputtered HZO and CSD yttrium-doped HZO (Y-HZO) films, indium-tin-oxide (ITO) was deposited by sputtering on sputtered HZO or CSD Y-HZO layer to fabricate metal-ferroelectric-semiconductor (MFS) structure
-
Low-voltage carbon nanotube complementary electronics using chemical doping to tune the threshold voltage Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-18 Fu Wen Tan, Jun Hirotani, Yoshiyuki Nonoguchi, Shigeru Kishimoto, Hiromichi Kataura, Yutaka Ohno
Simultaneous controlling of the threshold voltage of both p- and n-type transistors, comprising complementary integrated circuits, is required to develop low-voltage and low-power flexible electronics. In this study, we report tuning the threshold voltage of carbon nanotube thin-film transistors with organic and metal-ion complex salts as dopants, and using device passivation to secure air-stability
-
Efficient light-trapping sheet for the entire visible spectrum by using stacked concentric grating couplers Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-18 Seiji Nishiwaki, Youhei Morita, Michihiko Takase
We confirmed the effectiveness of light-trapping by forming concentric grating couplers (CGCs) inside a transparent sheet. A portion of the light incident to the CGCs is input-coupled and converted to the guided mode and is radiated from neighboring CGCs at a wider angle than the incident angle or even over the critical angle for both surfaces of the sheet. We demonstrated that three stacked sheets
-
First demonstration of X-band AlGaN/GaN high electron mobility transistors using free-standing AlN substrate over 15Wmm−1 output power density Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-18 Shiro Ozaki, Junya Yaita, Atsushi Yamada, Yusuke Kumazaki, Yuichi Minoura, Toshihiro Ohki, Naoya Okamoto, Norikazu Nakamura, Junji Kotani
In this letter, we successfully achieved high-power radio frequency (RF) operation of AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on free-standing AlN substrate at X-band. The developed HEMT on AlN substrate comprised a 200nmthick GaN channel and AlGaN buffer with an Al composition of 30%. Thanks to high breakdown voltage of the HEMT on AlN substrate, we successfully demonstrated
-
Planar head wave induced by pulsed laser ablation in liquid Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-18 Thao Thi Phuong Nguyen, Rie Tanabe-Yamagishi, Yoshiro Ito
We studied the dynamics of nanosecond-pulsed laser ablation of graphite-coated and black-paint-coated targets in liquids using a custom-designed time-resolved photoelasticity imaging technique. We presented the first demonstration of a planar head wave that was almost parallel to the target surface. In the solid, we observed a planar stress wave that was a counterpart of the planar head wave. This
-
Characteristics of terahertz wave emissions under the coexistence of different sub-picosecond transient phenomena in GaAs epitaxial films Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-18 Takayuki Hasegawa, Yuta Okushima, Yoshihito Tanaka
We report on the characteristics of the terahertz waveform originating from both the nonequilibrium transport of photogenerated carriers and the longitudinal optical phonon-plasmon coupled mode in GaAs epitaxial structures having a built-in electric field. The terahertz waveforms at different pump fluences were analyzed by an equation for the coherent oscillations of plasmons and phonons in addition
-
Blue semipolar InGaN microcavity light-emitting diode with varying cavity lengths from 113 to 290nm Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-16 Joonho Back, Vincent Rienzi, Matthew S. Wong, Hongjian Li, Steven P. DenBaars, Claude Weisbuch, Shuji Nakamura
Blue semipolar InGaN microcavity light-emitting diodes (MC-LEDs) with geometrical cavity lengths of 113, 205 and 290nm were fabricated, demonstrating the feasibility of ultra-thin MC-LEDs. Precise positioning of the active layer in the cavity is shown to be possible. The peak external quantum efficiencies (EQEs) of 113nm cavity length MC-LEDs with quantum well (QW) positions at 46%, 60% and 75% of
-
Discriminative sensing of temperature and acoustic impedance by using forward Brillouin scattering in large effective area fiber Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-16 Zelin Zhang, Yuangang Lu, Yosuke Tanaka, Jianqin Peng, Zhikang Zhuang
We experimentally clarified the characteristics of forward Brillouin scattering induced by radial acoustic modes (R 0,m ) in large effective area fiber. The measured resonance frequencies of R 0,m modes were shown to have different sensitivities to acoustic impedance. Then we performed discriminative measurement of temperature and acoustic impedance by selecting a pair of different R 0,m modes that
-
The tunable one-way transmission of Lamb waves by using giant magnetostrictive materials Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-16 Xiaowei Xue, Peng Li, Feng Jin
The methodology to realize the tunable one-way transmission of Lamb waves is proposed by using giant magnetostrictive materials. The elasticity of Terfenol-D is sensitive to the external magnetic fields, based on which the one-way transmission anti-symmetric and symmetric Lamb waves is achieved via non-symmetric magnetic field distributions imposed on Terfenol-D, and exemplified by numerical simulations
-
Highly tunable dual bound states in the continuum in bulk Dirac semimetal metasurface Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-10 Changchun Ma, Qi Lin, Lingling Wang, Kai Huang
We present a bulk Dirac semimetal (BDS) metasurface to realize tunable dual bound states in the continuums (BICs). The dual polarization-dependent BICs can transform into quasi-BICs with EIT or Fano lineshapes by breaking the structural symmetry. The excitation of quasi-BICs can attribute to the coupling between magnetic quadrupole mode and electric dipole mode (quasi-BIC I), or the coupling of two
-
Mechanical-stressing measurements of formation energy of single Shockley stacking faults in 4H-SiC Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-10 Koji Maeda, Koichi Murata, Isaho Kamata, Hidekazu Tsuchida
The formation energy of single Shockley stacking faults (1SSFs) in thermo-equilibrium is crucial for validating the anomalous expansion mechanism of 1SSF induced by forward current injection in 4H-SiC bipolar devices. As a function of variable mechanical stress externally applied to a plate sample of 4H-SiC, we systematically measured the ultraviolet intensity thresholds demarcating photo-induced expansion
-
Insight into segregation sites for oxygen impurities at grain boundaries in silicon Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-08 Yutaka Ohno, Jie Ren, Shingo Tanaka, Masanori Kohyama, Koji Inoue, Yasuo Shimizu, Yasuyoshi Nagai, Hideto Yoshida
The three-dimensional distribution of oxygen atoms segregated at Σ9{114} grain boundaries (GBs) in Czochralski-grown silicon ingots is analyzed within a high spatial resolution of less than 0.5nm by atom probe tomography combined with a focused ion beam (FIB) operated at −150 C. The analysis reveals a segregation of oxygen atoms within a range of 2.5nm across the GB plane, which is much narrower in
-
Reconfigurable liquid electromagnetic metamaterials driven by magnetic fields Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-08 Xiaochang Xing, Xiaoyong Tian, Xinyu Jia, Dichen Li
We propose a reconfigurable electromagnetic metamaterial device driven by magnetic fields. A field-driven reconfigurable metamaterial component (FD-RMC) consisting of periodic channels and compound liquid medium is fabricated. The transition of the electromagnetic metamaterial device from an absorbing state to a frequency-selective state is realized by placing the FD-RMC filled with a compound liquid
-
Nanocomposite fabricated by low energy silver ions implanted into dielectrics and sensitive to the refractive index of overlay Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-04 Jiaxian Zhao, Lun Qu, Jun Wang, Changlong Liu
Based on 30keV silver ions at a fluence of 6נ1016ionscm−2 implanted into SiO2, Al2O3 and YAG, we found that the nanocomposite layers embedded with silver nanoparticles are sensitive to the refractive index of overlays on the implanted surface. By dropping liquids with different refractive indices on the surface of nanocomposite layer, the reflection spectra of the rear surface would shift. The sample
-
Effects of thermal expansion and degeneracy on ambipolar carrier mobility of non-peripherally hexyl-substituted phthalocyanine Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-04 Masataka Fujisaki, Akihiko Fujii, Makoto Yoneya, Norimitsu Tohnai, Masanori Ozaki
The origin of the negative temperature dependence of carrier mobility in a crystal phase of 1,4,8,11,15,18,22,25-octahexylphthalocyanine was studied by utilizing a charge transport simulation based on Marcus theory and density functional theory. In order to understand the unique negative temperature dependence of carrier mobility, the theoretical calculation was carried out by taking the thermal expansion
-
Pulsed azimuthally polarized beam from passively Q-switched rotating Nd:YAG disk laser Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-03 San-Bin Chen, Jian-Lang Li, Ken-Ichi Ueda
A azimuthally polarized laser pulse was produced from a passively Q-switched rotating Nd:YAG disk laser with a Cr4+:YAG crystal as the saturable absorber and a uniaxial YVO4 crystal as the polarization selection. The averaged laser power reached 5.04W with a slope efficiency of 40%. The laser pulse had a maximum peak power of 4.3kW, minimum pulse duration of 31.07ns, and a 37.3kHz repetition rate at
-
Thermal mismatch induced stress characterization by dynamic resonance based on diamond MEMS Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-03 Huanying Sun, Xiulin Shen, Liwen Sang, Masataka Imura, Yasuo Koide, Jianqiang You, Tie-Fu Li, Satoshi Koizumi, Meiyong Liao
We report on the precise measurement of the thermal mismatch induced stress by dynamic resonance method. The metallic electrodes are deposited on a single-crystal diamond microelectromechanical resonator for the Joule heating and stress generation. The results show that the resonance frequency is linearly dependent on the induced stress. The stress resolution in this work is as precise as 104 Pa, which
-
Experimental demonstration of GaN IMPATT diode at X-band Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-03 Seiya Kawasaki, Yuto Ando, Manato Deki, Hirotaka Watanabe, Atsushi Tanaka, Shugo Nitta, Yoshio Honda, Manabu Arai, Hiroshi Amano
We report the first experimental demonstration of microwave oscillation in GaN impact ionization avalanche time transit (IMPATT) diodes at the X-band. The device used in this study is a single drift diode with a p+–n simple abrupt junction and vertical mesa termination. The reverse I–V characteristic of the diode shows low leakage current, clear avalanche breakdown, and high avalanche capability, as
-
Toward the megapixel live electrooptic imaging technique Appl. Phys. Express (IF 3.086) Pub Date : 2021-03-02 Masahiro Tsuchiya, Taku Sato, Atsushi Komuro
High-resolution electrooptic images have been successfully acquired, whose pixel number of 0.2M is a record-high for the non-scanning acquisition of high-frequency electric field distributions and is a triple of the conventional record. The image acquisition was conducted using a megapixel image sensor, where the reduction in the pixel number from 1 to 0.2M is due to unessential vignetting and can
-
Fabrication of GaN cantilever on GaN substrate by photo-electrochemical etching Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Takehiro Yamada, Yuto Ando, Hirotaka Watanabe, Yuta Furusawa, Atsushi Tanaka, Manato Deki, Shugo Nitta, Yoshio Honda, Jun Suda, Hiroshi Amano
Photo-electrochemical (PEC) etching is a promising technique for fabricating GaN microelectromechanical systems devices. In this study, we demonstrate the fabrication of GaN cantilevers by the bandgap-selective PEC etching of an InGaN superlattice sacrificial layer. By using an InGaN superlattice as a sacrifice layer, we found the PEC etching rate became higher than using a normal InGaN layer. As a
-
Enhanced microwave absorption performance of ultra-small Zn-doped Fe-C nanoparticles Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Daitao Kuang, Linlin Liu, Lizhen Hou, Heng Luo, Lianwen Deng, Min Song, Shiliang Wang
Ultra-small Zn-doped and non-doped Fe-C nanoparticles are synthesized by one-step metal-organic chemical vapour deposition. Zn-doped Fe-C nanoparticles exhibit an optimal minimum reflection loss of −63.6dB and a broad effective bandwidth of 7.8GHz at a thickness of 2.0mm, which is clearly superior over non-doped Fe-C nanoparticles. A comparative study suggests that the enhanced microwave absorption
-
High-quality AlN/sapphire templates prepared by thermal cycle annealing for high-performance ultraviolet light-emitting diodes Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Ding Wang, Kenjiro Uesugi, Shiyu Xiao, Kenji Norimatsu, Hideto Miyake
Thermal cycle annealing (TCA) is introduced to accelerate the dislocation annihilation in sputter-deposited AlN films on sapphire. Compared with constant temperature annealing, AlN films processed by TCA showed lower dislocation densities, smoother surface morphology, and fewer defects generated from the AlN/sapphire interface. After optimizing the film thickness, AlN films with a thickness of 800nm
-
Eu-doped GaN and InGaN monolithically stacked full-color LEDs with a wide color gamut Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Shuhei Ichikawa, Keishi Shiomi, Takaya Morikawa, Dolf Timmerman, Yutaka Sasaki, Jun Tatebayashi, Yasufumi Fujiwara
High-density micro light-emitting diode (μ-LED) arrays are key to next-generation ultrahigh-resolution displays. As a novel candidate, we report monolithic vertically stacked full-color LEDs consisting of Eu-doped GaN and InGaN quantum wells (QWs). Initially growing Eu-doped GaN, which shows a narrow linewidth ultra-stable red emission, allows vertically stacked growth of subsequent InGaN-QW-based
-
Light-induced persistent resonance frequency shift of MoS2 mechanical resonator Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Taichi Inoue, Tetsuki Saito, Kuniharu Takei, Takayuki Arie, Yasumitsu Miyata, Seiji Akita
We investigate light-induced persistent resonance frequency shift on MoS2 mechanical resonators towards optically tunable nano-electro-mechanical systems with optical memory function. After the termination of light irradiation, the resonance frequency shifts downwards and the downshift is maintained for more than 20min. This behavior is induced by trapped photogenerated holes at defects or contamination
-
Quantitative phase imaging of cells through turbid media based on infrared digital holographic microscopy Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Junsheng Lu, Yanan Zeng, Xinyu Chang, Yujian Hong, Xiaodong Hu
Most biological cells live in turbid media that poses an obstacle to real-time measurement of morphology, which is significant in the biomedical field. Imaging through turbid environments is experimentally challenging using visible-light illumination for multiple scattering. Therefore, an infrared digital holographic method is reported herein to test biological samples through turbid media that can
-
Enhanced nonradiative recombination in Al x Ga1−x N-based quantum wells thinner than the critical layer thickness determined by X-ray diffraction Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-25 Shuhei Ichikawa, Mitsuru Funato, Yoichi Kawakami
The optical properties of Al x Ga1−x N-based quantum wells (QWs) with various thicknesses are investigated. When the Al x Ga1−x N thickness in Al0.8Ga0.2N/AlN QWs exceeds 6 nm, the photoluminescence lifetime is drastically shortened even at cryogenic temperatures, which indicates that nonradiative recombination processes are enhanced. Interestingly, the thicknesses for the degradation of the optical
-
Surface structure of quasi-2D perovskite PEA2m MA n−2m Pb n I3n (n ≫ m) Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-24 Abduheber Mirzehmet, Tomoki Ohtsuka, Syed A. Abd. Rahman, Takumi Aihara, Muhammad Akmal Kamarudin, Shahrir Razey Sahamir, Shuzi Hayase, Tomoki Yuyama, Peter Krger, Hiroyuki Yoshida
Quasi-2D perovskites passivate the perovskite surface and improve the lifetime of perovskite solar cells. However, their detailed surface structures have never been reported. We studied the surfaces of the solution-processed quasi-2D PEA2m MA n−2m Pb n I3n (PEA: C6H5CH3CH2NH3, MA: CH3NH3) perovskites as well as the 2D perovskite formed on top of 3D MAPbI3 with the thicknesses relevant to practical
-
Origin of the material dependence of temperature coefficient of redox potential in conjugated polymers Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-24 Hiroki Iwaizumi, Dai Inoue, Takeshi Yasuda, Yutaka Moritomo
The thermal coefficient α (=d V/d T) of the redox potential (V) is an important physical parameter for thermal energy harvesting. To clarify the microscopic origin of α in conjugated polymers, we compared α and the physical quantity obtained by a quantum chemistry calculation in typical polymers with small monomer molecular weight. We observed a strong correlation between α and the number (N active)
-
Performance characteristics of strained Ge p-FinFETs under the integration of lattice and self-heating stress enabled by process-oriented finite element simulation Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-24 Chang-Chun Lee, Chia-Ping Hsieh, Pei-Chen Huang, Ming-Han Liao
Stress-induced mechanism and related manifold characteristics from lattice mismatch and harsh self-heating effect (SHE) substantially interact are major concerns of advanced strained Ge p-FinFETs with inherent poor thermal conductivity. This study presents a process-oriented simulation methodology to investigate the comprehensive influences composed of the stress amplitude and performance variations
-
Fast acquisition of spin-wave dispersion by compressed sensing Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-23 Ryo Kainuma, Keita Matsumoto, Takuya Satoh
For the realization of magnonic devices, spin-wave dispersions need to be identified. Recently, the time-resolved pump-probe imaging method combined with the Fourier transform was demonstrated for obtaining the dispersions in the lower-wavenumber regime. However, the measurement takes a long time when the sampling rate is sufficiently high. Here, we demonstrated the fast acquisition of spin-wave dispersions
-
Probing the effects of surface roughness and barrier layer thickness in InAlGaN/GaN HEMTs to improve carrier mobility Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-20 Junya Yaita, Atsuthi Yamada, Norikazu Nakamura, Junji Kotani
In this study, we investigated the effects of the thickness and surface roughness of InAlGaN barrier layers on the electron mobility of InAlGaN/GaN high-electron-mobility transistors (HEMTs) with low sheet resistance for applications at high frequencies. The results indicate that the carrier electron mobility of InAlGaN/GaN HEMTs decreases with barrier thickness. This is mainly due to the surface roughness
-
Deep-learning-based semantic image segmentation of graphene field-effect transistors Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-19 Shota Ushiba, Naruto Miyakawa, Naoya Ito, Ayumi Shinagawa, Tomomi Nakano, Tsuyoshi Okino, Hiroki K. Sato, Yuka Oka, Madoka Nishio, Takao Ono, Yasushi Kanai, Seiji Innami, Shinsuke Tani, Masahiko Kimuara, Kazuhiko Matstumoto
Large-scale graphene films are available, which enables the integration of graphene field-effect transistor (G-FET) arrays on chips. However, the transfer characteristics are not identical but diverse over the array. Optical microscopy is widely used to inspect G-FETs, but quantitative evaluation of the optical images is challenging as they are not classified. Here, we implemented a deep-learning-based
-
Gate voltage dependence of noise distribution in radio-frequency reflectometry in gallium arsenide quantum dots Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-19 Motoya Shinozaki, Yui Muto, Takahito Kitada, Takashi Nakajima, Matthieu R. Delbecq, Jun Yoneda, Kenta Takeda, Akito Noiri, Takumi Ito, Arne Ludwig, Andreas D. Wieck, Seigo Tarucha, Tomohiro Otsuka
We investigate gate voltage dependence of electrical readout noise in high-speed rf reflectometry using gallium arsenide quantum dots. The fast Fourier transform spectrum from the real time measurement reflects build-in device noise and circuit noise including the resonator and the amplifier. We separate their noise spectral components by model analysis. Detail of gate voltage dependence of the flicker
-
GaN-based MIS-HEMTs with Al2O3 dielectric deposited by low-cost and environmental-friendly mist-CVD technique Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-17 Rui Shan Low, Joel T. Asubar, Ali Baratov, Shunsuke Kamiya, Itsuki Nagase, Shun Urano, Shinsaku Kawabata, Hirokuni Tokuda, Masaaki Kuzuhara, Yusui Nakamura, Kenta Naito, Tomohiro Motoyama, Zenji Yatabe
We report on the fabrication and characterization of AlGaN/GaN metal-insulator-semiconductor (MIS) capacitors and high-electron-mobility transistors (MIS-HEMTs) using a 5nmthick Al2O3 dielectric deposited by cost-effective and environmental-friendly mist chemical vapor deposition (mist-CVD) technique. Practically hysteresis-free capacitance–voltage profiles were obtained from the fabricated two-terminal
-
Strain induced abnormal grain growth in thermally oxidized Cu2O sheets Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-17 Garima Aggarwal, Akhilender Jeet Singh, Hitesh Kumar Mehtani, K. R. Balasubramaniam
Strain induced abnormal grain growth (SIAGG) has been of great interest in metals and metallic alloys but only limited studies of this interesting phenomenon exist in bulk metal oxides. Here, we demonstrate SIAGG in thermally oxidized Cu2O by cold-working the Cu-foil prior to oxidation. During the cold-work, dislocation density increases at edges and this inhomogeneity in the microstructure give rise
-
Time-resolved mid-infrared photoluminescence from highly strained InAs/InGaAs quantum wells grown on InP substrates Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-12 Hisashi Sumikura, Tomonari Sato, Akihiko Shinya, Masaya Notomi
We measured time-resolved mid-infrared photoluminescence (PL) from highly strained InAs/InGaAs quantum wells (QWs) grown on InP substrates with a wavelength up-conversion technique. The InAs QWs at 4K exhibit a narrow PL peaked at a wavelength of 2.125μm and a PL lifetime as long as 1.1ns, which supports high homogeneity of the QW thickness and few defects. As the pump fluence increases, a fast PL
-
THz emission from a Bi2Sr2CaCu2O8+δ cross-whisker junction Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-12 Yoshito Saito, Shintaro Adachi, Ryo Matsumoto, Masanori Nagao, Shuma Fujita, Ken Hayama, Kensei Terashima, Hiroyuki Takeya, Itsuhiro Kakeya, Yoshihiko Takano
Cuprate superconductor Bi2Sr2CaCu2O8+δ (BSCCO) has been a promising candidate of a coherent, continuous, and compact THz light source owing to its intrinsic Josephson junction (IJJ) inside the crystal structure. In this paper, we utilized BSCCO cross-whisker (CW) junctions to produce THz emitter device using the whisker crystals which can be easily obtained compared with single crystals. As a result
-
Si grating structure for surface plasmon resonance excitation by back-side normal incidence illumination Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-11 Yoshiki Saito, Shinichi Suzuki, Tetsuo Kan
We propose a structure suitable for surface plasmon resonance (SPR) excitation with light incident on the back-side of the device, which has affinity with the semiconductor process. We constructed a diffraction grating on the top layer of a silicon-on-insulator wafer and completely embedded the grating in a polymer. According to a reflectance measurement, SPR could be efficiently excited, and its behavior
-
Effect of ionic conduction under dielectric barriers on PEDOT:PSS electrochemical interfaces Appl. Phys. Express (IF 3.086) Pub Date : 2021-02-11 Yasutoshi Jimbo, Wonryung Lee, Masaya Nishinaka, Tomoyuki Yokota, Takao Someya
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been widely used for electrochemical interfaces. When the surface is covered by an inhomogeneous dielectric layer, ions are injected to the uncovered part of PEDOT:PSS and then laterally diffuse to the covered part. However, this effect has not been incorporated into the device model. Here we show the effect of lateral ionic diffusion
Contents have been reproduced by permission of the publishers.