-
Single-frequency high-energy pulses from an Er:Yb glass planar waveguide amplifier with good beam quality Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-17 Junia Nomura, Kenichi Hirosawa and Nobuo Ohata
We demonstrate a master oscillator power amplifier system that emits single-frequency, high-energy optical pulses at 1539 nm using an Er, Yb:glass planar waveguide amplifier with a normalized frequency of the waveguide of 4.4. A maximum pulse energy of 9.7 mJ is observed at a repetition frequency of 500 Hz. The signal to noise ratio is 25 dB and is independent of the repetition frequency from 100 to
-
High-power, stable single-mode CW operation of 1550 nm wavelength InP-based photonic-crystal surface-emitting lasers Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-17 Takeshi Aoki, Yuhki Itoh, Kosuke Fujii, Hiroyuki Yoshinaga, Naoki Fujiwara, Makoto Ogasawara, Yusuke Sawada, Rei Tanaka, Hideki Yagi, Masaki Yanagisawa, Masahiro Yoshida, Takuya Inoue, Menaka De Zoysa, Kenji Ishizaki and Susumu Noda
1550 nm wavelength photonic-crystal surface-emitting lasers (PCSELs) are attractive for optical communication and eye-safe sensing applications. In this study, we present InP-based PCSELs featuring a double-lattice photonic-crystal structure designed for high-power single-mode operation at a wavelength of 1550 nm. These PCSELs demonstrate output powers exceeding 300 mW under continuous-wave conditions
-
Three-step field-plated β-Ga2O3 Schottky barrier diodes and heterojunction diodes with sub-1 V turn-on and kilovolt-class breakdown Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-17 Advait Gilankar, Ahmad Ehteshamul Islam, Martha R. McCartney, Abishek Katta, Nabasindhu Das, David J. Smith, Nidhin Kurian Kalarickal
A unique field termination structure combining a three-step field plate with nitrogen ion implantation to enhance the reverse breakdown performance of Pt/β-Ga2O3 Schottky barrier diodes (SBDs) and NiO/β-Ga2O3 heterojunction diodes (HJDs) is reported. The fabricated devices showed a low R on,sp of 6.2 mΩ cm2 for SBDs and 6.8 mΩ cm2 for HJDs. HJDs showed a 0.8 V turn-on voltage along with an ideality
-
Single-longitudinal-mode vortex Nd:YVO4 laser using a circular Dammann grating for pump shaping Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-17 Jiaxin Song, Junjie Yu, Weilin Cao, Yuefei Li, Dawei Zhang, Jianlang Li
In this research, a 1064 nm single-longitudinal-mode (SLM) vortex beam was generated from an annular-pumped Nd:YVO4 microchip laser, in which a circular Dammann grating was used to reshape the 808 nm pump light into an annular intensity profile. As a result, the laser emitted a SLM LG01 beam with a maximum output power of 192 mW. A straightforward technique for producing SLM vortex beams is made available
-
Rejuvenation of degraded Zener diodes with the electron wind force Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-17 Md Hafijur Rahman, Nahid Sultan Al-Mamun, Nicholas Glavin, Aman Haque, Fan Ren, Stephen Pearton, Douglas E. Wolfe
In this study, we explore the rejuvenation of a Zener diode degraded by high electrical stress, leading to a leftward shift, and broadening of the Zener breakdown voltage knee, alongside a 57% reduction in forward current. We employed a non-thermal annealing method involving high-density electric pulses with short pulse width and low frequency. The annealing process took <30 s at near-ambient temperature
-
First principles study on the time-related properties of 4H-32SiC as an energy converting material of betavoltaic batteries Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-12 Xiaoyi Li, Jingbin Lu, Xinrui Liu, Yu Zhang, Yuxin Liu, Yuehui Zhang, Fubo Tian
The radioactive 4H-32SiC is applied as an energy converting material to fabricate high performance betavoltaic batteries. The time-related component change is considered, and the structural, stability and electrical property changes are calculated by density functional theory. As time goes by, the number of 32Si atoms decrease exponentially while the concentration of 32S increases gradually. The Si63PC64
-
Selective phase transition of cholesteric blue phase I induced by pattern-controlled Grandjean–Cano disclinations Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-12 Kazuma Nakajima, Shogo Mitsuhashi, Masanori Ozaki
This study investigates the influence of Grandjean–Cano disclinations on the cholesteric-blue phase I (Ch-BPI) phase transition, revealing the pivotal role of defects in the phase transition of liquid crystals (LCs). We prepared the disclinations by wedge cells or parallel cells with an alignment pattern and demonstrated that the disclinations induce a phase transition in Ch-BPI. Furthermore, we demonstrated
-
Plasma–ionic liquid-assisted CO2 capture and conversion: A novel technology Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-08 Pankaj Attri, Kazunori Koga, Jamoliddin Razzokov, Takamasa Okumura, Kunihiro Kamataki, Tomohiro Nozaki, Masaharu Shiratani
The present study focused on CO2 capture, storage, and conversion through the innovative integration of plasma–ionic liquid (IL) technology. For the first time, we employed plasma-IL technology to confront climate change challenges. We utilized 1-Butyl-3-methylimidazolium chloride IL to capture and store CO2 under atmospheric pressure, and subsequently employed plasma to induce the transformation of
-
Broadband heterodyne electro-optic sampling using a lithium niobate ridge-waveguide Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-08 S. Mine, G. Gandubert, J. E. Nkeck, X. Ropagnol, K. Murate, F. Blanchard
We demonstrated the bandwidth broadening of terahertz waves detected by heterodyne electro-optical sampling by implementing a ridge waveguide structure in a lithium niobate (LiNbO3) crystal. Such an approach effectively reduces absorption loss, eases the phase matching condition and enhances the nonlinear interaction length through the optical confinement effect. As a result, we have more than doubled
-
Diode-pumped 88 fs SESAM mode-locked Tm,Ho:CLNGG laser at 2090 nm Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-05 Anna Suzuki, Yicheng Wang, Sergei Tomilov, Zhongben Pan, Clara J. Saraceno
We report on a passively mode-locked Tm,Ho:CLNGG laser operating at 2090 nm, pumped by a multimode fiber-coupled 793 nm laser diode, representing the first demonstration of a diode-pumped sub-100-fs mode-locked laser at 2.1 μm wavelength. Due to the disordered nature of the gain material that exhibits a broad and smooth gain profile, pulses as short as 88 fs were achieved with an average output power
-
Drift suppression of solution-gated graphene field-effect transistors through electrolyte submersion Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-05 Shota Ushiba, Yuka Tokuda, Tomomi Nakano, Takao Ono, Shinsuke Tani, Masahiko Kimura, Kazuhiko Matsumoto
In solution-gated graphene FETs (SG-GFETs), cations in electrolyte solutions can intercalate between graphene and SiO2. Such permeation affects substrate-induced hole doping effects, resulting in drifts in the charge neutrality point (CNP) of SG-GFETs. In this study, we investigated the effect of submerging GFETs in electrolyte solutions on CNP values. The results revealed that the CNP decreased considerably
-
Near-infrared phosphorescent OLEDs exhibiting over 10% external quantum efficiency and extremely long lifetime using resonant energy transfer with a phosphorescent assist dopant Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-05 Takanori Hanayama, Takeshi Sano, Yu Saito, Takeru Nakamura, Yutaka Okuyama, Hisahiro Sasabe, Junji Kido
We have introduced a three-component light-emitting layer consisting of a host, a phosphorescent assist dopant, and a phosphorescent emitter to simultaneously realize high efficiency and long lifetime in NIR organic LEDs. An efficient energy transfer between the two phosphorescent materials was observed with 1 wt% doping ratio of the NIR emitter, significantly enhancing the external quantum efficiency
-
Development of a method for analyzing the positional correlation of local structures in scanning probe microscopy images using template-matching image-processing method Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-02 Sota Tsubokura, Shoya Kawano, Yumiko Imai, Tadashi Ueda, Kei-ichi Nakamoto, Haruo Noma, Hirohisa Hioki and Taketoshi Minato
The functionalities of materials are governed by the atom type and arrangement, and perturbations caused by defects and adsorbate interactions often significantly alter the behavior of materials. Scanning probe microscopy (SPM) can capture complex interactions caused by the structures on surfaces. It is, however, difficult to analyze such interactions appearing there. In this paper, an image-processing
-
Anomalous deformation behavior of Ag nanowires on Au electrode in low-temperature environments Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-01 Yuichi Watanabe, Kazunori Kuribara and Ken-ichi Nomura
We discovered that Ag nanowires (AgNWs) on an Au electrode exhibited an anomalous deformation behavior despite a low-temperature environment of 65 °C. Most AgNWs on the Au electrode were deformed after heating. In contrast, AgNWs on the Cr and Ag electrodes exhibited a few changes and maintained their initial shape. The deformation behavior of AgNWs on metal electrodes has not yet been reported and
-
Terahertz resonant-tunneling-diode oscillator with two offset-fed slot-ring antennas Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-01 Shoei Endo and Safumi Suzuki
We proposed and fabricated a terahertz resonant-tunneling-diode oscillator integrated with two offset slot-ring antennas for high-output power and high-directivity radiation. In this device, the length of the antenna, approximately half the wavelength of the oscillation frequency, enables efficient terahertz radiation. The increased radiation conductance, resulting from the offset and the two slot-ring
-
Temperature dependence of power transfer efficiency and power handling capability of wireless power transfer system using superconducting bulk coil Appl. Phys. Express (IF 2.3) Pub Date : 2024-04-01 Natsuka Oshimoto, Takanori Fujita, Keita Sakuma and Naoto Sekiya
We developed a cryocooler system to reveal the temperature dependence of the quality (Q) factor of high-temperature superconducting (HTS) bulk coil and the power transfer efficiency (PTE) and power handling capability (PHC) of a wireless power transfer (WPT) system using the HTS bulk coil. The measured Q factors of the HTS bulk coil were 9051 at 77 K and 14 050 at 25 K. The measured PTEs and PHCs of
-
Low-field transport properties and scattering mechanisms of degenerate n-GaN by sputtering from a liquid Ga target Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-28 P. Döring, T. Tschirky
In this work, degenerate n-type GaN thin films prepared by co-sputtering from a liquid Ga-target were demonstrated and their low-field scattering mechanisms are described. Extremely high donor concentrations above 3 × 1020 cm−3 at low process temperatures (<800 °C) with specific resistivities below 0.5 mΩcm were achieved. The degenerate nature of the sputtered films was verified via temperature-dependent
-
Temperature- and magnetic field-induced magnetic structural changes in the Fe3Si/FeSi2 superlattice Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-22 Takayasu Hanashima, Jun-ichi Suzuki, Kazuhisa Kakurai, Noboru Miyata, Ken-ichiro Sakai, Hiroyuki Deguchi, Yoshiaki Hara, Satoshi Takeichi, Tsuyoshi Yoshitake
Artificial lattices with semiconductor spacers are expected to exhibit changes in their magnetic structure owing to the control of their electronic states. The temperature (T) and magnetic-field (H ext) dependence of the in-plane magnetic structure of an [Fe3Si/FeSi2]20 superlattice with a nonmagnetic and semiconducting FeSi2 spacer layer is investigated using magnetization and polarized neutron reflectivity
-
Facile and controllable chemical doping of conducting polymers with an ionic liquid dopant Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-18 Hisaaki Tanaka, Shun-ichiro Ito, Toru Matsui, Taishi Takenobu
A facile method for chemical doping of conducting polymers is demonstrated with an ionic liquid containing FeCl4 − anions as the oxidizing agents. A drop of the ionic liquid on the film of a typical semicrystalline polymer immediately changed the room temperature conductivity to 500 S cm−1. The highly conductive state originated from both the high doping level and the high crystallinity of the doped
-
Field-free magnetization switching with full scale in Pt/Tm3Fe5O12 bilayer on vicinal substrate Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-15 Tianhui Li, Weikai Luo, Jinxiang Wu, Xinjun Li, Hui Yang, Xiaotian Zhao, Hongyu An
The spin–orbit torques within a Pt/Tm3Fe5O12 (TmIG) bilayer offer an expedient method for manipulating the magnetization of TmIG. However, the practical application of TmIG is hindered by the presence of an external field during switching. Here, we demonstrate field-free magnetization switching in Pt/TmIG bilayer on a vicinal substrate with minimal sacrifice to the perpendicular magnetic anisotropy
-
Realizing reliable linearity and forming-free property in conductive bridging random access memory synapse by alloy electrode engineering Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-15 Ao Chen, Puyi Zhang, Yiwei Zheng, Xiaoxu Yuan, Guokun Ma, Yiheng Rao, Houzhao Wan, Nengfan Liu, Qin Chen, Daohong Yang, Hao Wang
The linearity of conductance modulation of the artificial synapse severely restricts the recognition accuracy and the convergence rate in the learning of artificial neural networks. In this work, by alloy electrode engineering, a Ti–Ag device gained the forming-free property because Ag ions were promoted to migrate into the GeTeOx layer to form a thicker conductive filament. This facilitated a uniform
-
Structural modulation of bilayer graphene under an external electric field and carrier doping Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-15 Nadia Sultana, Yanlin Gao, Mina Maruyama, Susumu Okada
Density functional theory was used to investigate the geometric structure of bilayer graphene under an external electric field with carrier doping. Our calculations revealed the crucial impact of external electric fields and the hole injection on determining the geometric structure of bilayer graphene. The bond length of graphene monotonically increased when increasing the hole doping concentration
-
Evaluation of polar alignment structure and surface anchoring energy in ferroelectric nematic liquid crystals by renormalized transmission spectroscopic ellipsometry Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-14 Sakunosuke Abe, Amon Nakagawa, Yosei Shibata, Munehiro Kimura, Tadashi Akahane
It is essential to estimate the surface polar anchoring energy in order to discuss the interfacial orientation of ferroelectric nematic liquid crystals. In this study, we accurately estimated the twist angle of a π -twist cell with an antiparallel rubbing manner, by means of renormalized transmission spectroscopic ellipsometry, which has a great deal of experience in measuring the twist angle of ordinary
-
A simple reflective metalens based on reverse design for an ultra-high-efficiency free space wavelength splitter Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-12 Chao Wang, Yunpeng Hao, Boqi Wu, Fan Yang, Chunlei Zhao, Yaodan Chi, Xiaotian Yang
We propose two kinds of high-efficiency free-space wave splitters in the mid-IR band using reverse design. The wavelength divider based on the abnormal reflection principle realizes a beam-splitting angle of 22.00° and 10.92° by controlling the phase distribution, and the reflection efficiency of both wavelengths exceeds 50%. The wavelength divider designed based on the concept of metalens simultaneously
-
Multibeam X-ray tomography optical system for narrow-energy-bandwidth synchrotron radiation Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-11 Wolfgang Voegeli, Haruki Takayama, Xiaoyu Liang, Tetsuroh Shirasawa, Etsuo Arakawa, Hiroyuki Kudo, Wataru Yashiro
The design and evaluation experiments of a multibeam X-ray tomography optical system that can be used with synchrotron radiation from sources with a narrow energy bandwidth, i.e. undulator sources, are reported. It consists of silicon single crystals that diffract the incident X-rays to 27 beams, which are used to image a sample. The energy of the beams was aligned with an accuracy sufficient for use
-
8.7 A/700 V β-Ga2O3 Schottky barrier diode demonstrated by oxygen annealing combined with self-aligned mesa termination Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-11 Feihong Wu, Zhao Han, Jinyang Liu, Yuangang Wang, Weibing Hao, Xuanze Zhou, Guangwei Xu, Yuanjie Lv, Zhihong Feng, Shibing Long
β-Ga2O3 Schottky barrier diodes (SBDs) with low-defect epitaxial surface and effective termination are essential for realizing excellent blocking characteristics. This work systematically studied oxygen annealing at various temperatures, optimizing the epitaxial surface by reducing the surface roughness and dislocation density. Combined with mesa termination, the results showed that the breakdown voltage
-
Electrical properties and band alignments of Sb2Te3/Si heterojunctions, low-barrier Sb2Te3/n-Si and high-barrier Sb2Te3/p-Si junctions Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-08 Naoya Okada, Wen Hsin Chang, Shogo Hatayama, Yuta Saito, Toshifumi Irisawa
We investigated the electrical junction properties of the layered Sb2Te3 film formed on Si substrates. The current−voltage characteristics of the Sb2Te3/n-Si heterojunction showed an ohmic properties, whereas the Sb2Te3/p-Si heterojunction exhibited rectifying properties with a high barrier height of 0.77 eV. The capacitance−voltage characteristics of MOS capacitors with the Sb2Te3 electrode indicated
-
Improvement of film quality and solar cell properties of perovskite by the addition of N-benzylhydroxylamine Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-07 Keisuke Nagasawa, Takeshi Sano, Viet Nguyen Chau, Yutaka Okuyama, Yuya Sayama, Ryosuke Oikawa, Keigo Hoshi, Takayuki Chiba, Junji Kido
In this study on perovskite solar cells (PVSCs), we incorporate N-benzylhydroxylamine (N-BzHoA) as an additive into the precursor solution. The addition of N-BzHoA suppressed the formation of unwanted PbI2 and δ-phase perovskite without affecting the band gap, confirming uniform and large grains in the perovskite film. The fabricated inverted PVSCs exhibited remarkably improved properties compared
-
Nanosecond recombination lifetimes and spin relaxation times in (110) InGaAs/AlGaAs quantum wells at room temperature Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-06 Satoshi Iba, Yuzo Ohno
Quantum wells in InGaAs/AlGaAs with (110) orientation are attractive as active layers in spin-controlled lasers with circularly polarized emission, while the spin relaxation time is expected to be larger than for (100)-oriented layers. However, the hitherto reported recombination lifetimes (40 ps) and spin relaxation times (440 ps) of (110) InGaAs/AlGaAs structures are insufficient. Here it is shown
-
Lightweight and high-precision materials property prediction using pre-trained Graph Neural Networks and its application to a small dataset Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-06 Kento Nishio, Kiyou Shibata, Teruyasu Mizoguchi
Large data sets are essential for building deep learning models. However, generating large datasets with higher theoretical levels and larger computational models remains difficult due to the high cost of first-principles calculation. Here, we propose a lightweight and highly accurate machine learning approach using pre-trained Graph Neural Networks (GNNs) for industrially important but difficult to
-
Multi-focus manipulation system based on separable natural evolution strategy aberration self-calibration Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-06 Linxian Liu, Jiahao Liu, Chunxu Ding, Jiamiao Yang, Jia Gao, Yuan Qu, Qiaozhi He, Rongjun Shao
Wavefront shaping using digital micromirror devices (DMDs) allows inertia-free focus manipulation with numerous modulation modes and high refresh rates. However, the aberration caused by the curvature of DMDs affects the focusing performance. Here, we propose an aberration self-calibration method based on separable natural evolution strategies. This method searches optimal Zernike coefficients of aberration
-
A two-stage insulation method for suppressing thermal crosstalk in microarray sensitive units Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-06 Shining Zhu, Xin Li, Zhengjie Luo, Xuguang Jia, Yue Qin, Hao Guo, Jun Tang, Zhonghao Li, Huanfei Wen, Zongmin Ma, Jun Liu
Thermal crosstalk between array structures is a key factor in limiting the sensitivity of micro-nano array sensors. We propose a two-stage thermally isolated structure with thermal holes and heat dissipation layer and pulsed voltage heating to reduce thermal crosstalk. Through finite element thermal simulation analysis as well as thermal interference test, the results show that the thermal crosstalk
-
Extraction of interfacial thermal resistance across an organic/semiconductor interface using optical-interference contactless thermometry Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-06 Jiawen Yu, Hiroaki Hanafusa, Seiichiro Higashi
We have developed an experimental method to extract interfacial thermal resistance (ITR) at an organic/semiconductor interface based on optical-interference contactless thermometry. The proposed technique was applied to a SU-8/SiC bilayer sample, and clear oscillations in reflectivity induced by optical interference during pulse heating and cooling were observed. After fitting the observed reflectivity
-
Realization of low specific-contact-resistance on N-polar GaN surfaces using heavily-Ge-doped n-type GaN films deposited by low-temperature reactive sputtering technique Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-04 Shinji Yamada, Masanori Shirai, Hiroki Kobayashi, Manabu Arai, Tetsu Kachi, Jun Suda
We developed a low-temperature ohmic contact formation process for N-polar GaN surfaces. Specific-contact-resistances of 9.4 × 10−5 and 2.0 × 10−5 Ω cm2 were obtained using Ti/Al metal stacks on heavily-germanium-doped GaN films, which were deposited at 500 °C and 600 °C using a radical-assisted reactive sputtering method, respectively. The electrode sintering temperature was as low as 475 °C. Carrier
-
Magnetic field tuning of photoelectric and photoluminescence effects in BiFe0.9Co0.1O3 thin film Appl. Phys. Express (IF 2.3) Pub Date : 2024-03-04 Guanzhong Huo, Jinyan Li, Chao Su, Hongyu Xu, Guilin Chen, Shuiyuan Chen
The reported BiFe0.9Co0.1O3 film presents an interesting magnetic field tunning effect on the photoelectric properties and photoluminescence spectra. The change rate of the photocurrent up to 123.6% was achieved when applying a 400 Oe magnetic field to the film, which is attributed to the spin scattering of photoelectrons in the film. The experimental result of the magnetic field tuning photoluminescence
-
Inverted input method for computing performance enhancement of the ion-gating reservoir Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-27 Yu Yamaguchi, Daiki Nishioka, Wataru Namiki, Takashi Tsuchiya, Masataka Imura, Yasuo Koide, Tohru Higuchi, Kazuya Terabe
Physical reservoir computing (PRC) is useful for edge computing, although the challenge is to improve computational performance. In this study, we developed an inverted input method, the inverted input is additionally applied to a physical reservoir together with the original input, to improve the performance of the ion-gating reservoir. The error in the second-order nonlinear equation task was 7.3
-
Tesla-class single-cycle terahertz magnetic field pulses generated with a spiral-shaped metal microstructure Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-26 Kei Maruyama, Zhenya Zhang, Miharu Takumi, Takuya Satoh, Makoto Nakajima, Yoshihiko Kanemitsu, Hideki Hirori
We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with NIR light. The determined magnetic field strength and field-enhancement spectrum are
-
A time-delayed physical reservoir with various time constants Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-23 Yutaro Yamazaki, Kentaro Kinoshita
Physical reservoir computing has been attracting attention in recent years. However, it remains unclear how much nonlinearity is required in the physical dynamics to achieve a high computational performance. Therefore, we focused on a resistor–capacitor circuit, which exhibits simple transient characteristics, and investigated the performance required for a physical reservoir. As a result, the proposed
-
Development of nanostructured Ge/C anodes with a multistacking layer fabricated via Ar high-pressure sputtering for high-capacity Li+-ion batteries Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-23 Tomoki Omae, Teruya Yamada, Daiki Fujikake, Takahiro Kozawa, Giichiro Uchida
To realize high-capacity Ge anodes for next-generation Li+-ion batteries, a multilayer anode with a C(top)/Ge(middle)/C(bottom) structure was developed, where nanostructured amorphous Ge (a-Ge) and amorphous-like carbon films with a grain size of 10–20 nm were deposited sequentially by high-pressure Ar sputtering at 500 mTorr. Compared with the a-Ge anode, the C(top)/a-Ge(middle)/C(bottom) multistacking
-
Flexible light-induced self-written optical waveguide with 50 μm core size Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-21 Ryo Futawatari, Hidetaka Terasawa, Okihiro Sugihara
We demonstrate a NIR light-induced self-written (LISW) optical waveguide between graded-index (GI) glass optical fibers with a 50 μm core size (50GIFs) using gel material. We describe the optical properties of the LISW optical solder in terms of its flexibility, adhesiveness, and loss. The results demonstrate that the two 50GIFs were self-coupled through the LISW optical waveguide, and the connection
-
Epitaxial ZnO piezoelectric layer on SiO2/Mo solidly mounted resonator fabricated using epitaxial Au sacrificial layer Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-21 Satoshi Tokai, Takahiko Yanagitani
In solidly mounted resonator (SMR) type of bulk acoustic wave resonator, it is difficult to fabricate single crystalline piezoelectric thin films in a bottom-up process due to the amorphous SiO2 in the low acoustic impedance layer of the acoustic Bragg reflector. In this study, single crystalline ZnO piezoelectric layer on amorphous SiO2/polycrystalline Mo acoustic Bragg reflector is fabricated using
-
Temperature dependence of liquid-gallium ordering on the surface of epitaxially grown GaN Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-20 Takuo Sasaki, Takuya Iwata, Kanya Sugitani, Takahiro Kawamura, Toru Akiyama, Masamitu Takahasi
The three-dimensional ordering of the gallium (Ga) adlayers on GaN(0001) and (000 1¯ ) surfaces was probed using in situ X-ray scattering under MBE conditions. An ordered bilayer of Ga forms on GaN(0001) but the ordering decreases at substrate temperatures of <450 °C, consistent with the mechanism of non-equilibrium epitaxial growth. Monolayer Ga that forms on GaN(000 1¯ ) is laterally disordered and
-
Demonstration of recycling process for GaN substrates using laser slicing technique towards cost reduction of GaN vertical power MOSFETs Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-20 Takashi Ishida, Takashi Ushijima, Shosuke Nakabayashi, Kozo Kato, Takayuki Koyama, Yoshitaka Nagasato, Junji Ohara, Shinichi Hoshi, Masatake Nagaya, Kazukuni Hara, Takashi Kanemura, Masato Taki, Toshiki Yui, Keisuke Hara, Daisuke Kawaguchi, Koji Kuno, Tetsuya Osajima, Jun Kojima, Tsutomu Uesugi, Atsushi Tanaka, Chiaki Sasaoka, Shoichi Onda, Jun Suda
To address the issue of the high cost of GaN substrates, a recycling process for GaN substrates using a laser slicing technique was investigated. The channel properties of lateral MOSFETs and the reverse characteristics of vertical PN diodes, which represent the main components of vertical power devices, exhibited no degradation either before and after laser slicing or due to the overall GaN substrate
-
Suppression of electromagnetic crosstalk by differential excitation for SAW generation Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-15 Shunsuke Ota, Yuma Okazaki, Shuji Nakamura, Takehiko Oe, Hermann Sellier, Christopher Bäuerle, Nobu-Hisa Kaneko, Tetsuo Kodera, Shintaro Takada
Surface acoustic waves (SAWs) hold a vast potential in various fields such as spintronics, quantum acoustics, and electron-quantum optics, but an electromagnetic wave emanating from SAW generation circuits has often been a major hurdle. Here, we investigate a differential excitation method of interdigital transducers to generate SAWs while reducing the electromagnetic wave. The results show that electromagnetic
-
Single-photon level ultrafast time-resolved measurement using two-color dual-comb-based asynchronous linear optical sampling Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-14 Prasad Koviri, Hajime Komori, Haochen Tian, Masahiro Ishizeki, Takashi Kato, Akifumi Asahara, Ryosuke Shimizu, Thomas R. Schibli, Kaoru Minoshima
We demonstrated an ultrafast time-resolved measurement method operating at the single-photon level and employing a two-color comb-based asynchronous optical sampling (ASOPS) setup. We harnessed the two-color ASOPS photon counting approach to achieve long-term averaging of the ultralow intensity signal with a synchronized optical trigger signal, which minimizes residual timing jitter between the two
-
Synthetic method of pure-red emissive CsPbI3 under ambient conditions for quantum-dot light-emitting diode application Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-07 Kenshin Yoshida, Naoaki Oshita, Taisei Kimura, Mao Goto, Ryosuke Oikawa, Mizuho Uwano, Satoshi Asakura, Takayuki Chiba, Akito Masuhara
Perovskite quantum dots (PeQDs) are expected to be used in ultra-high-definition television (UHDTV) due to their excellent optical properties. However, pure-red emissive (λ EL: 620–650 nm) PeQD-based LEDs (PeLEDs) are required for UHDTV with single-halogen PeQDs synthesized under ambient conditions, which is important for practical use. Hence, we established a novel synthetic method to prepare PeQDs
-
Voltage-controlled magnetic anisotropy effect through a high-k MgO/ZrO2/MgO hybrid tunneling barrier Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-02 Hiroshige Onoda, Tomohiro Nozaki, Takayuki Nozaki, Shinji Yuasa
We investigated the voltage-controlled magnetic anisotropy (VCMA) effect in epitaxial magnetic tunnel junctions (MTJs) with a hybrid MgO/ZrO2/MgO tunnel barrier. A metastable cubic ZrO2(001) thin film was successfully grown on a MgO(001) layer, leading to the high dielectric constant of 26.5. Using the hybrid tunneling barrier, we achieved the large VCMA coefficient of −350 fJ V−1 m−1, which is 70%
-
Higher-order resonance of single-crystal diamond cantilever sensors toward high f‧Q products Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-02 Guo Chen, Zilong Zhang, Keyun Gu, Liwen Sang, Satoshi Koizumi, Masaya Toda, Haitao Ye, Yasuo Koide, Zhaohui Huang, Meiyong Liao
MEMS resonant sensing devices require both HF (f) and low dissipation or high quality factor (Q) to ensure high sensitivity and high speed. In this study, we investigate the resonance properties and energy loss in the first three resonance modes, resulting in a significant increase in f‧Q product at higher orders. The third order resonance exhibits an approximately 15-fold increase in f‧Q product,
-
Realization of nociceptive receptors based on Mott memristors Appl. Phys. Express (IF 2.3) Pub Date : 2024-02-01 Yanji Wang, Yu Wang, Yanzhong Zhang, Xinpeng Wang, Hao Zhang, Rongqing Xu, Yi Tong
Nociceptive receptors are primarily responsible for detecting and responding to potentially harmful stimuli, including painful sensations and tissue damage. In this letter, we designed Pt/Ag/NbO x /W memristors with threshold switching (TS) characteristics and low working voltage attributed to the diffusion of Ag ions within the device. Furthermore, this device successfully emulates the functions of
-
Analysis and measurement of high frequency piezoelectric ring resonator Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-30 Tingting Yang, Yao Cai, Chao Gao, Qinwen Xu, Yang Zou, Yan Liu, Wenjuan Liu, Cheng Lei, Chengliang Sun
This paper introduces a piezoelectric ring resonator, comprising a Mo-ScAlN-Mo sandwich structure and shaped into a ring with a hollow center. The vibrational modes of the resonator are elucidated through simulation and theoretical analysis, and the impact of diverse geometric parameters on the resonant frequency is explored. A HF resonator with a resonance frequency of 4.168 GHz has been fabricated
-
Core–shell yarn-structured triboelectric nanogenerator for harvesting both waterdrop and biomechanics energies Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-29 Haitao Wang, Yasuyoshi Kurokawa, Jia-Han Zhang, Kazuhiro Gotoh, Xin Liu, Satoru Miyamoto, Noritaka Usami
Wearable energy harvesters (WEHs) have garnered significant attention recently due to their promising capabilities in powering wearable devices. In this research, we present a core–shell yarn-structured triboelectric nanogenerator (CY-TENG) that operates in two modes: the single-electrode TENG (SE-TENG) and the droplet-based electricity generator. This design facilitates energy harvesting from both
-
Printed organic transistors and complementary ring oscillators operatable at 200 mV Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-24 Masaya Yamada, Yasunori Takeda, Shizuo Tokito, Hiroyuki Matsui
Applications of organic thin-film transistors (OTFTs) include wearable health monitors and next-generation Internet-of-Things systems driven by a small energy-harvesting power supply. Such applications require low voltage and low power consumption organic ICs. In this paper, we demonstrate complementary ICs based on printed p-type and n-type OTFTs operatable at an ultralow supply voltage of 200 mV
-
Cathodoluminescence spectral and lifetime mapping of Cs4PbBr6: fast lifetime and its scintillator application Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-24 Tetsuya Kubota, Sotatsu Yanagimoto, Hikaru Saito, Keiichirou Akiba, Ayumi Ishii, Takumi Sannomiya
Highly efficient green emission of Cs4PbBr6 has been attributed to intermediate states formed by embedded CsPbBr3 nanocrystals or defects. However, direct experimental confirmation of the presence of such nano-emitters is not straightforward and the emission mechanism remains elusive. By using cathodoluminescence (CL) imaging with a high spatial resolution, we demonstrate that CsPbBr3 nanocrystals
-
The optical gain variation of Ge nanowires induced by L-valley splitting under the [110] direction stress Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-24 Xin Li, Ning Hou, Wen Xiong
The electronic structures of Ge nanowires under the [110] direction stress are calculated via effective-mass k·p theory, and the results manifest eight equivalent L-valleys will be split into fourfold degenerate L 1-valleys and L 2-valleys. With increasing stress, the electron levels at the L 1-valleys and L 2-valleys can be pushed close to and away from those at the Γ-valley, respectively, which causes
-
Density functional theory study on the effect of NO annealing for SiC(0001) surface with atomic-scale steps Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-19 Mitsuharu Uemoto, Nahoto Funaki, Kazuma Yokota, Takuji Hosoi, Tomoya Ono
The effect of NO annealing on the electronic structures of the 4H-SiC(0001)/SiO2 interface with atomic-scale steps is investigated. The characteristic behavior of conduction band edge (CBE) states is strongly affected by the atomic configurations in the SiO2 and the step structure, resulting in the discontinuity of the CBE states at the step edges, which prevents electrons from penetrating from the
-
Scattering-free Ce:LYBO single crystals for thermal neutron detection Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-17 Dongsheng Yuan, Encarnación G. Víllora, Daisuke Nakauchi, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida, Kiyoshi Shimamura
Ce:Li6Y(BO3)3 (LYBO) is a well-known candidate for thermal neutron detection with a very high Li concentration (3.06 × 1022/cm3). So far, as-grown crystals exhibit a milky appearance that compromises their performance as scintillators. Current work demonstrates, for the first time, the growth of scattering-free undoped and Ce-doped LYBO by a thermal quenching process. The origin and features of the
-
Hollow Mie resonators based on toroidal magnetic dipole mode with enhanced sensitivity in refractometric sensing Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-17 Rongyang Xu, Junichi Takahara
We propose a refractometric sensor based on hollow silicon Mie resonators of a toroidal magnetic dipole mode. This mode has a pair of antiparallel electric dipoles perpendicular to the silica substrate; thus, the radiation of the mode is suppressed, resulting in an ultra-narrow reflection peak linewidth of 0.35 nm. In addition, the hollow structure enhances the interaction between the enhanced electric
-
Phononic band calculations and experimental imaging of topological boundary modes in a hexagonal flexural wave machine Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-16 Hayato Takeda, Ryoya Minami, Osamu Matsuda, Oliver B. Wright, Motonobu Tomoda
We construct a two-dimensional mechanical wave machine based on a hexagonal lattice to investigate low-frequency flexural plate waves whose propagation mimicks a topological quantum valley Hall system. We thereby demonstrate “mechanical graphene” by extension of the one-dimensional Shive wave machine to two dimensions. Imaging experiments, backed up by simulations, reveal the presence of boundary modes
-
Time-resolved force microscopy using the delay-time modulation method Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-09 Hiroyuki Mogi, Rin Wakabayashi, Shoji Yoshida, Yusuke Arashida, Atsushi Taninaka, Katsuya Iwaya, Takeshi Miura, Osamu Takeuchi, Hidemi Shigekawa
We developed a time-resolved force microscopy technique by integrating atomic force microscopy using a tuning-fork-type cantilever with the delay time modulation method for optical pump-probe light. We successfully measured the dynamics of surface recombination and diffusion of photoexcited carriers in bulk WSe2, which is challenging owing to the effect of the tunneling current in time-resolved scanning
-
High-pressure plasma etching up to 9 atm toward uniform processing inside narrow grooves of high-precision X-ray crystal optics Appl. Phys. Express (IF 2.3) Pub Date : 2024-01-08 Shotaro Matsumura, Iori Ogasahara, Masafumi Miyake, Taito Osaka, Daisetsu Toh, Jumpei Yamada, Makina Yabashi, Kazuto Yamauchi, Yasuhisa Sano
We developed a new etching technique using plasma generated at high pressure up to 9 atm. Operating at 9-atm pressure with a 30-μm-diameter wire electrode, we demonstrated the generation of well-ordered plasma at a narrow gap of ∼10 μm between the electrode and workpiece, and realized a high spatial resolution of <40 μm during processing. This technique should allow for the processing of high-precision