publications & presentations | research & development | rohm semiconductor-ag凯发旗舰厅

shunsuke akasaka

ieej transactions on electrical and electronic engineering

kento kariya

journal of smart processing for materials environment & energy, volume: 12, issue: 5, pp. 251-256

keisuke wakamoto

japanese journal of applied physics, volume: vol. 61, pp. sd1029

keisuke wakamoto

ieee transactions on components, packaging and manufacturing technology, volume:13, pp. 197-210

keisuke wakamoto

experimental techniques

sputtered β-ga2o3 crystallization by high temperature annealing on aln/si

akira sagawa

ssdm2023

tatsuya yanagi

epe 2023 ecce europe

shogo ogawa

ieee transactions on electron devices

development of a high-speed and high-accuracy sic mosfet model applicable to circuit and system simulators

yohei nakamura

電気学会産業応用部門シンポジウム

application of remote epitaxy for sic wafer cost reduction

takuji maekawa

workshop on advanced epitaxy for freestanding membranes and 2d materials

performance comparison between igbt and sic during wltc

hirokatsu umegami

パワーエレクトロニクス学会第248回定例研究会

extremely small limiting-current-type oxygen sensor with a wide range proportionality of the oxygen concentration

shunsuke akasaka

we succeeded in demonstrating an oxygen microsensor with a good linear relationship in a wide-range oxygen concentration.

transducers2023

positioning analysis of semconductor companies for specidfic technology using bert

saya ueda

this study proposes a method to identify trends and positions: differences between companies of specific technology, especially semiconductor package in this paper, by using the published patent information. our approach in this study is to generate document vectors by bert to get clusters with characteristics which are found in one company but not the other, use word2vec to analyze these clusters for each vector related to technology, and understand them by engineers' feedback to clarify the difference of technology orientation between the two companies.
as a result, the document vectors related to semiconductor packaging technology shows a company has the strength in light emitting field, and the other has in magnetic one.

2023年度 人工知能学会全国大会（第37回）

suppression of leakage current in wireless charging systems using n-legged inverters

yusaku takagi (tokyo university)

wireless power transfer systems using n-leg inverters are known to cause leakage current to flow to the non-driven legs when some of the legs are driven, which is caused by charging and discharging to the depletion capacitance of the device. we found that the suppression effect differs depending on the pulse length. this pulse length dependence was confirmed by circuit simulations and experiments.

ieee wireless power technology conference and expo (wptce)

characteristic improvement of mems-type ultrasonic device with controllable natural frequencies

takashi kimura

we have developed an ultrasonic oscillation device using a piezoelectric film, in which the natural frequency can be controlled within a range sufficient for application.

第40回強誘電体会議

simplified open-loop transfer functions to analyze influential parasitic parameters for oscillation caused by parallel connected transistors

hiroto sakai

oscillation may occur during parallel connection in switching devices. the authors have established a method to easily derive an approximate formula for the open-loop transfer function to evaluate the stability of the oscillation phenomenon. the derived approximate formula enables us to analyze the influence of parasitic parameters of both devices and modules on the oscillation, including their interaction. the dependence on the parameters identified by the formula was confirmed to be correct by simulation and experiment.

ispsd 2023

conducted noise evaluation of dual-half bridge pfc converter

yuta okawauchi

totem-pole pfcs are being put to practical use because of their high efficiency, but they generate large common mode noise when the ac voltage polarity is switched. we have developed a dual half-bridge pfc that can reduce common-mode noise, and confirmed that conducted noise can be reduced by using actual equipment.

電気学会　家電・民生研究会

autonomous minimization of power loss by switching frequency adjusting function for a dc–dc converter

junichi kashiwagi

the authors present a dc-dc converter that autonomously adjusts the switching frequency and reduces losses.

pcim2023

a unified model of mis and ridge hemts for fast and high-power switching applications.

hitoshi aoki

invited paper: algan/gan mis-hemt and algan/gan ridge hemt are implemented in one verilog-a compact model. the theory and practice of modelling features for each normally-off device will be discussed. in addition, the issues of parasitic device characteristics and scaling by esfps are raised and solutions are presented. this paper presents the key technologies for a number of papers that have been published so far.

12th international conference on communications, circuits and systems (icccas)

hirokatsu umegami

world electric vehicle journal, volume: 14, issue: 4, apr. 2023, pp.

アプリケーション視点重視のパワーエレクトロニクス研究開発

ken nakahara

wide-gap semiconductors such as silicon carbide (sic) and gallium nitride (gan) has reportedly improved the characterisitics of power devices. however, imporved device characteristics does not automatically create a new value in power applications. this paper discusses what kind of research should be conducted from the viewpoint of power application values, and reports rohm's r&d activities along with this r&d direction.

公益社団法人精密工学会

structural optimization of toroidal coils based on neural network and explainable ai

kuniyoshi okamoto

this study proposes a method that can obtain highly convincing optimal conditions in a short time by explainable ai technology for device structure optimization using a neural network model and an optimization algorithm.

第70回　応用物理学会　春季学術講演会

population estimation of characteristic variation in power transistors

haruka fukumoto

第70回　応用物理学会　春季学術講演会

degradation mechanism of sintered silver die attach by thermal and mechanical cycling test

keisuke wakamoto

sic chip die bonding with sintered nano silver layer was evaluated by thermal cycle test and nine point bending test (nbt). nbt is an original bending test that can mecahnically apply out-of-plane deformation to the die attached assembles as tst like. we propose the new damage parameter associated with both experiments, and we will clarify the overall sintered silver die degradation mechanism during reliability tests.

日本実装学会春季講演大会

n相インバータを用いたn-1コイル非接触給電システムにおけるパルスによる待機電流抑制

yusaku takagi

wireless power transfer systems using n-leg inverters are known to cause leakage current to flow in non-driven legs when some of the legs are driven. using circuit analysis, we found that the leakage current is caused by charging and discharging to the depletion capacitance of the device. we also found that a method to suppress the standby current is to input short pulses to the non-driven legs.

電気学会研究会 電力技術一般ならび半導体電力変換一般

対向ターゲット式スパッタした cofeb-sio 2 薄膜 を用いた長方形型スパイラルコイル

honami nitta (tokyo institute of technology)

we report the results of a spiral coil using a new anisotropic magnetic material.

電気学会全国大会

enhancement of linear-polarization degree of emitted beam from photonic-crystal surface-emitting lasers (pcsels)

eiji miyai

photonic crystal lasers (pcsels) enable both high-power operation and high-quality beam, thus they are useful for various application. in a certain optical system, linear polarization of the beam can be important. thus, based on optimization by quantum annealing, we realized the beam with high polarization degree by control of the lattice-point shape and current-density distribution.

第70回応用物理学会春季学術講演会

proposal for a market investigation method based on time series analysis of multiple information resources written in natural language.

saya ueda

we propose a method to validate the market relevancy of r&d themes. we conducted a hot-word analysis for representative words of r&d themes using word2vec, using as input several information resources written in different natural languages, such as technology news and patent databases. the target was to provide a quick and objective overview of the market in a field where objective statistical data such as market size is not yet clear or where there is a monopoly and other areas are difficult to see.

言語処理学会第29回年次大会(nlp2023)

tolerance of eigenfrequencies in the su-schrieffer-heeger electrical circuit

fumiya nagasawa

応用物理学会 春季学術講演会

sic wafer cost reduction with remote epitaxy technology

takuji maekawa

sic industry is growing fast and delivering highly efficient and compact power electronics. the main contributor of sic device cost is sic substrate. other costs such as epitaxy and fabrication costs are low compared to sic substrate cost. in this talk, the author introduces the first application of remote epitaxy technology through graphene to sic alternative substrates with epi membranes. the author believes that this epi-based substrate is the solution to cost savings for sic wafers.

acers ema 2023 / electronic materials and applications

principal component analysis based gan transistor live health monitoring

florian chalvin

a method using pca to track gan transistors degradation in real time with no need for prior failure data is investigated. based on the fatigue experiment carried out we suggest a graphical representation and associated threshold to easily detect when a device is damaged.

issm2022

research on the correlation between power devices and power systems

ken nakahara

wide-gap semiconductors have recently been attracting much attention, but it is still not easy to claim that what values new-semiconductor devices are capable of providing for power applications. the authores set up the research and development project that bridge the gap between applications and devices. the team drive a electric vehicle motor with silicon carbide (sic) transistors, simulated driving according to an internationally common driving mode, and calculate its electric mileage. the results showed that sic is superior to si devices in all the driving modes.

先進パワー半導体分科会第9回講演会

sintered silver degradation assessment by thermal and mechanical cyclic tests

keisuke wakamoto

this reseach investigates the two types of sintered silver (s-ag) die layer (np: nano paste, nmp, nano to micro paste) delamination speed main cause by compating thermal shocked test (tst) and nine point bending test (nbt). nbt can mechcanically apply out-plane deformation for s-ag die part as tst provides. the obtained results suggest that nbt could organize delamination ratio during tst. that was, mechanical stress was main contribution to the failure of s-ag die layer during tst.

icmr2022

a secondary-side resonant llc converter for reducing resonance voltage with boost mode operation using resonance including current doubler rectifier

hayato nakamura（okayama university）

a new circuit topology is proposed to realize a boost mode in a secondary-side resonant llc converter by utilizing the magnetizing inductance of a coupled inductor placed on the secondary side, and its effectiveness is verified by simulation and actual measurement.

spec2022 (southern power electronics conference)

yohei nakamura

ieee transactions on power electronics

nine point bending test technique for evaluating the sintered silver die degradation

keisuke wakamoto

this reseach introduces new mechanical bending test technique called nine-point-bending test (nbt). nbt can mechanically provide out-ou-plane deformation as tst provides. in the presentation, state the technical components in nbt, then the sintered silver die failure mechanism during tst will be discussed by comparing the results of nbt.

the 19th international conference on precision engineering

compact and cost-effective solution for terahertz applications

beziko mikhail

overview of resonant tunneling diode devices developed at rohm. key advantages and characteristics.

electronica 2022 embedded platforms conference

degradation mechanism comparison of sintered silver die in thermal and mechanical cycling tests

keisuke wakamoto

we proposed nine-point bending test technique that can apply out-of-plane deformation to the assembly, which is similar with the defomation morphorogy during tst. by comparing nbt and tst, degradation during tst was mainly given rise by the mechanical stress.

mnc 2022, 35th international microprocesses and nanotechnology conference

oxygen and humidity sensing property of a limiting current-type thin-film ysz-based sensor on a micro-hotplate

shunsuke akasaka

sensing properties of mems oxygen and humidity sensor

ieee sensors 2022

evaluating sintered silver die-attach thermal cycling degradation

keisuke wakamoto

in this paper, we investigated the sintered silver (s-ag) degradation mechanism during thermal shocked test (tst).
during tst, the s-ag degradation was multiply given rise by thermal and mechanical stress. to clarify the main degradation cause during tst, reliability study separately should be performed to focus on the main degradation cause. hereby, nine-point bending test that can be applied out-ou-plane deformation to the assemble is proposed. by comparing between nbt and tst, s-ag degradation mechanism is discussed.

ssdm2022

effects of underside-si annealing on charge breakdown of lpcvd sin film

hayato miyagawa (kagawa university: joint research with rohm hamamatsu co., ltd.)

the dependence mechanism of sin film breakdown on the n2 annealing temperature was investigated using tddb and esr. we proposed two types of tddb modes at 900℃　and over 1000℃. at the first mode of 900℃, sin film breakdown frequency due to the generation of si dangling bonds with one oxygen and two silicon back bonds.　at the second mode　over 1000℃, sin film breakdown frequency, caused by the e’center, which is si dangling bonds with three oxygens. in previous paper, si reconstruction occur in h2 or ar annealing at from 850℃ to 1200℃. to determine the effect of sin/si interface reconstruction behavior at 900℃, we add si　annealing before sin film deposition.

第83回応用物理学会秋季学術講演会

control of current distribution for enhanced robustness of single-mode oscillation in a photonic-crystal surface-emitting laser

eiji miyai

photonic crystal lasers (pcsel) are characterized by being capable of large-area single-mode operation. however, when the current becomes high, it may become multimode depending on the lattice point shape. therefore, in order to suppress multimode oscillation and improve the robustness of the design, theoretical analysis was performed by making the injection current density distribution gaussian. as a result, it was found that the gaussian current density distribution suppressed multimode oscillation compared to the normal electrode.

第83回応用物理学会秋季学術講演会

sintered silver die degradation evaluation by nine point bending test technique

keisuke wakamoto

日本機械学会年次記念大会

size reduction in imaging system using a single resonant tunneling diode transceiver

ryoko mizuno（osaka university）

電子情報通信学会ソサイエティ大会

自動車用パワーエレクトロニクスの現状と動向

ryosuke ishido

this paper reports on the current power devices used in electric vehicles.

電気学会産業応用部門大会

loss minimization of ac filter inductor for three-phase pwm inverter using neural network

taisei yamaguchi

電気学会産業応用部門大会

sic wafer cost reduction strategy with remote epitaxy

takuji maekawa

sic industry is growing fast and delivering highly efficient and compact power electronics. the main contributor of sic device cost is sic substrate. other costs such as epitaxy and fabrication costs are low compared to sic substrate cost. in this talk, the author introduces the first application of remote epitaxy technology through graphene to sic alternative substrates with epi membranes. the author believes that this epi-based substrate is the solution to cost savings for sic wafers.

workshop on advanced epitaxy for freestanding membranes and 2d materials

the rise of power semiconductors: correlation analysis of specific words used in internal reports &external news

saya ueda

this study uses natural language processing to analyze the correlation based on "internal company reports" and "external reports," between news about technology and the market formation trends of products developed with the company’s proprietary technology.in the case of sic, specific market-related words could be extracted from two years before the sales expansion. on the other hand, no such words could be extracted for gan.

2022年度 人工知能学会全国大会（第36回）

performance comparison of si igbt and sic mosfet power module driving ipmsm or im under wltc

hirokatsu umegami

infineon si igbt and rohm sic mosfet of 2, 3 and 4 generation is compared by evaluating characteristic of powertrain loss and energy consumption with ipmsm and im under road load of nissan leaf and bmw i4 edrive.

evs35

effect of n2-anneal temperature on silicon nitride film:(ⅱ) fine structures of esr spectrum and ftir

hayato miyagawa (kagawa university: joint research with rohm hamamatsu co., ltd.)

the dependence mechanism of sin film breakdown on the n2 annealing temperature was investigated using tddb, esr and ftir. we proposed two types of tddb modes at 900℃ and over 1000℃. at the first mode of 900℃, sin film breakdown frequency due to the generation of si dangling bonds with one oxygen and two silicon back bonds. at the second mode over 1000℃, sin film breakdown frequency, caused by the e’center, which is si dangling bonds with three oxygens.

241st ecs meeting

effect of n2-anneal temperature on silicon nitride film:(ⅰ) time-dependent dielectric breakdown and esr evaluations

hisatsugu kurita（ローム浜松）

the dependence mechanism of sin film breakdown on the n2 annealing temperature was investigated using tddb and esr. we proposed two types of tddb modes at 900℃ and over 1000℃. at the first mode of 900℃, sin film breakdown frequency due to the generation of si dangling bonds with one oxygen and two silicon back bonds. at the second mode over 1000℃, sin film breakdown frequency, caused by the e’center, which is si dangling bonds with three oxygens.

241st ecs meeting

an analysis of open-loop transfer function and effects of parasitic parameters for differential-mode oscillations between parallel switching devices

hiroto sakai

for oscillations between parallel switching devices in power modules, the open loop transfer function was derived approximately by extracting the dominant circuit elements for each frequency band from the equivalent circuit considering the high frequency parasitic component. in addition, the effect of each parameter on the poles and zeros on the bode plot was clarified from the derived approximation formula, and the parameter dependence was demonstrated by circuit simulation.

電気学会　産業応用部門　家電・民生研究会

an evaluation of a new type of high efficiency hybrid gate drive circuit for sic- mosfet suitable for automotive power electronics system applications

masayoshi yamamoto (名古屋大学)

a report about high efficiency hiblid gate driver for sic mosfet

電子情報通信学会

r&d bridging over device and system engineers through the electric-mileage estimation of a motor system.

ken nakahara

the team experimentally showed how different power devices change the efficiency of a motor system. this reserach aims at optimizing the design of the whole system, not focusing only on the device characteristics.

ipec2022

masayoshi yamamoto（nagoya university）

j-stage, volume: e105.a, issue: 5, may.2022, pp. 834-843

high efficiency 3-phase power inverter using sic mosfets and trans-linked neutral-point-clamped topology

tatsuya miyazaki

a 50kw three-phase inverter using sic mosfets achieves a maximum conversion efficiency of 99.1%. the inverter utilizes a neutral-point-clamped (npc) topology combined with a trans-linked circuit. these combined technologies successfully reduce the reactor loss and enable high efficiency operation.

apec2022

development of high speed and high accuracy sic mosfet model using vhdl-ams.

naotaka kuroda

令和4年度 電気学会全国大会

temperature characterizations of multi-unit and multi-finger dependencies on algan/gan

hitoshi aoki (teikyo heisei university)

the authors discuss the measurements and simulations of the transconductance characteristics for the compact model of algan/gan ridge type hemts that we have developed, focusing on the dependence on temperature, number of gate fingers and number of units. in particular, we proposed model equations for the increased drain current due to gate injection and discuss in detail the analysis results of the change in the gate injection current characteristics with device size and temperature.

34th ieee international conference on microelectronic test structures (icmts2022)

a method for extracting important technologies related to semiconductors using results of time-series data analysis of patent and sales information

saya ueda

this study proposes a method to extract "what is important technology" by performing natural language processing on patent documents. specifically, the method was applied to white led (light emitting diode) patent information from 1986 to 2010s. we found that the underlying technology was filed three years prior to the white led sales expansion.

言語処理学会第28回年次大会(nlp2022)

yohei nakamura

japanese journal of applied physics, volume: 61, issue: sc, mar.2022

norikazu ito

ieee electron device letters, volume: 43, issue: 2, dec.2021, pp. 192-195

naoaki tsurumi

acs omega, volume: 6, issue: 49, dec.2021, pp. 34173–34184

keiju sato(nagoya university)

communications materials, volume: 2, issue: 117, dec.2021

limiting current-type mems oxygen gas sensor integrated with micro-hotplate

shunsuke akasaka

a report about limiting current-tpe mems oxygen sensor. this report includes the fabrication method and sensing property of oxygen sensor.

ieee sensors 2021

comparison in sintered siiver die attach failure between thermal shocked test and four-point bending test

keisuke wakamoto

sintered silver (s-ag) has attracted so many researchers due to its high heat conductivity. applying power module products for die attach part, the degradation has been evaluated by thermal shocked test (tst). therefore, understanding of the degradation mechanism during tst is an eseential role for designing power modules. the objective of this study is to compare degradation mechanism between tst and four-point bending test to understand s-ag die attach failure in power module products under operation.

mnc2021

dominant model parameter extraction for analyzing current imbalance in parallel connected sic mosfets

yohei nakamura

sic mosfetの並列駆動時に生じる電流アンバランス動作に対する影響が支配的なモデルパラメータの抽出方法を提案する。抽出の結果、8個あるモデルパラメータの内、2個のパラメータの影響が支配的となる結果が得られた。

ecce2021

observation of a flat band in millimetre-scale magic-angle twisted bilayer graphene

wataru norimatsu (nagoya university)

the electronic states of twisted bilayer graphene (tbg) vary with its twist angle. in this study, we obtained 5 × 5 mm^2 tbg samples with various twist angle, using epi-graphene on sic. furthermore, angle-resolved photoemission spectroscopy revealed their energy band structures.

graphene week 2021

hollow-waveguide packaging of terahertz devices using photonic-crystal interface

yuma kawamoto(osaka university)

テラヘルツ帯デバイスの新たな導波管実装法として、フォトニック導波路をインタフェースとした実装法を提案した。本手法を用いて、共鳴トンネルダイオードを導波管に実装したモジュールを作製した。作製したモジュールを受信器として用いた300 ghz帯の無線通信実験を行い、17 gbit/sまでのエラーフリー無線伝送を得た。

電子情報通信学会ソサイエティ大会

300-ghz-band pam-4 wireless communications using resonant tunneling diode receiver

atsushi oshiro(osaka university)

共鳴トンネルダイオード（rtd）を受信器として用い、 300 ghz 帯において pulse amplitude modulation (pam)-4 無線通信実験を行った。rtdの負性抵抗領域における増幅作用を利用した検波動作により、48 gbit/s (24 gbaud)の通信速度を達成した。

電子情報通信学会ソサイエティ大会

lpcvd sin film breakdown and n2-anneal temperature (ⅱ) esr and ftir evaluations

hayato miyagawa (kagawa university: joint research with rohm hamamatsu co., ltd.)

the dependence mechanism of sin film breakdown on the n2 annealing temperature was investigated using tddb, esr and ftir. we proposed two types of tddb modes at 900℃ and over 1000℃. at the first mode of 900℃, sin film breakdown frequency due to the generation of si dangling bonds with one oxygen and two silicon back bonds. at the second mode over 1000℃, sin film breakdown frequency, caused by the e’center, which is si dangling bonds with three oxygens.

第82回応用物理学会秋季学術講演会

lpcvd sin film breakdown and n2-anneal temperature (ⅰ) tddb and esr evaluations

hisatsugu kurita (rohm hamamatsu co., ltd.)

the dependence mechanism of sin film breakdown on the n2 annealing temperature was investigated using tddb and esr. we proposed two types of tddb modes at 900℃ and over 1000℃. at the first mode of 900℃, sin film breakdown frequency due to the generation of si dangling bonds with one oxygen and two silicon back bonds. at the second mode over 1000℃, sin film breakdown frequency, caused by the e’center, which is si dangling bonds with three oxygens.

第82回応用物理学会秋季学術講演会

observation of a flat band in millimeter-schale magic-angle twisted belayer graphene

wataru norimatsu (nagoya university)

従来の方法では、ツイスト2層グラフェン（tbg）をバンド構造観察可能な試料サイズで作製することが困難であった。しかし当研究gはエピタキシャルグラフェンを用いることで大面積tbgを作製し、容易に評価可能となった（前回報告）。今回の報告では、魔法角を含む様々なツイスト角のtbgを作製し、バンド構造の直接観察を行った結果について報告する。

第86回応用物理学会秋季学術講演会

auto structural optimization of toroidal coils based on neural network and genetic algorithm

junichi kashiwagi

the toroidal coil shape was automatically optimized using neural networks and genetic algorithm.

epe2021

micro pore structure dependence on pressured-type sintered silver tensile mechanical properties

keisuke wakamoto

はんだ接合の代替技術として、高熱伝導・耐熱な接合を可能にする銀焼成接合技術が注目を集めている。しかし、接合過程でどうしても空孔を内部に含む。これまで筆者らは空孔率が6%以下に抑えることで耐久性の向上を実証した.今回は,加圧型銀焼成を用いて,空孔率を2～4%に制御し, 静的引張試験を実施した. 空孔サイズ・空孔率が低いほど高い耐久性を示した.

日本機械学会

experimental validation of thermal couple impedance model for accurate die temperature estimation in power modules

yohei nakamura

パワーモジュール内のチップ温度を精度良く見積もるために構築した熱インピーダンスモデルの実機検証を行った。構築したモデルは、実測のチップ温度を精度良く再現し、最大誤差は5℃以内であった。

ssdm2021

keisuke wakamoto

energies, volume: 14, issue: 17, sep.2021, pp. 5532

integrated resonant tunneling diode with rectangular waveguide i/o using photonic crystal interface

yuma kawamoto（osaka university）

we have developed a technology to integrate terahertz devices in rectangular waveguides with low loss by using dielectric transmission lines.
a module in which a resonant tunneling diode is packaged using a photonic crystal waveguide was fabricated, and wireless communication was demonstrated.

46th international conference on infrared, millimeter and terahertz waves

terahertz rtd chip backside-coupled to photonic-crystal waveguide

ratmalgre koala（osaka university）

we proposed a backside-coupling structure for efficient and broadband coupling of terahertz resonant tunneling diodes and phoonics-crystal waveguides, and demonstrated its operation in the 300-ghz band.

46th international conference on infared, millimeter and terahertz waves

sic wafer cost reduction with remote epitaxy technology through graphene

takuji maekawa

expanding sic power device market requires lowering wafer prices for the majority of device costs. in this talk, the author reports the application of remote epitaxy technology to alternative substrate with epi-membrane. sic remote epitaxy needs high growth temperature with hot-wall chemical vapor deposition around 1873 k, which is a harsh environment for graphene survival. by replacing the carrier gas from hydrogen to argon, graphene etching was suppressed and peeling was successful. the author believes this approach represents a significant step toward the fabrication of high quality and low cost substrate with epi.

epitaxy on 2d materials for layer release and their applications

geometry independent hole injection current model of gan ridge hemts

hitoshi aoki (teikyo heisei university)

the compact model of gan ridge hemts, especially the drain current increase due to gate injection, has been improved from the one presented at apec2020, and a scalable model equation has been derived by considering the physical generation mechanism. in addition, we analized the effect of the current gain h21 on the frequency response when the device is operated in ac. with this model, the h21 characteristics in the current-increasing region due to gate injection agreed with the actual measurement with high accuracy.

30th international symposium on industrial electronics (isie2021)

ev driving pattern simulation with plecs

ryosuke ishido

we propose a results of a simple motor inverter simulation with wltc droving mode using plecs. plecs is the simulation platform of power electric systems.

apec2021

takehito suzuki（tokyo university of agriculture and technology）

optics express, volume: 29, issue: 12, june.2021, pp. 18988-19000

direct observation of pzt thin film actuator cantilever displacement

tomohiro date

第38回強誘電体応用会議

tlp bonding process using in coated cu sheet for high-temperature dieattach

hiroshi nishikawa（osaka university）

in coated cu substrate was used as a low melting temperature bonding. we optimized the joint condition such as a temperature, pressure and process.

ectc

development of the third-generation wireless in-wheel motor

osamu shimizu(tokyo university)

the third-generation wireless in-wheel motor (w-iwm3) which has the capability of the dynamic wireless power transfer (d-wpt) on its wheel side has been developed for the electric vehicles. developing concepts of w-iwm3 targeting “all components in wheel” is realized. one of the factors for “all components in wheel” is the small silicon-carbide (sic) power device authors have developed. this paper showed the test result that the more than 18kw output with 95.2% dc to dc efficiency was achieved.

evtec 2021 5th international electric vehicle technology conference 2021

a high-speed and high-accuracy sic mosfet model for simulating practical power circuits

yohei nakamura

we propose a sic mosfet model for circuit simulation. we validated the accuracy of the proposed model by measured switching waveforms of an inductive load switching evaluation circuit. simulation speed of the model has been validated by a three-phase inverter simulation. excellent results have been observed for both accuracy and speed.

pcim2021

characterization of mechanical properties of pb-2sn-2.5ag solder using instrumented indentation microscopy with optically transparent indenter

kento kariya

pb-2sn-2.5ag alloy solder is one of the most popular materials for die attach in electronic devices, however its mechanical properties have not been reported. in this study, we measured the visco-elasto-plastic properties of pb-2sn-2.5ag solder using instrumented indentation microscopy with an optically transparent indenter.

22nd international conference on thermal, mechanical and multi-physics simulation and experiments in microelectronics and microsystems

study of the microstructure and the mechanical properties of pb-2.0sn-2.5ag solder joint

kento kariya

since high lead solder has been used in industry for many years, few basic studies have been reported that discuss the microstructure and mechanical properties. in this study, the relationship between the microstructure and mechanical properties of high lead solder joints was investigated.

2021 ieee international reliability physics symposium

フォトニック結晶レーザの広範囲温度動作

wataru kunishi

フォトニック結晶レーザの素子設計を改良することで、-40～100℃の温度範囲で、モードホップすることなくレーザ発振が得られることを確認。出力変動率は既製品fp-ldと同定が得られることも確認。

2021年第68回応用物理学会春季学術講演会

efficient coupling between valley photonic crystals waveguide and resonant tunneling diode

yuishiro yamagami（osaka university）

テラヘルツ帯導波路として有望なバレーフォトニック結晶導波路に対して電子デバイスを集積化することを目指し、導波路と金属線路の高効率結合に関する検討を行った。

2021年第68回応用物理学会春季学術講演会

terahertz pulse induced harmonic generation in resonant tunneling diode oscillator

takashiarikawa（kyoto university）

発振していない共鳴トンネルダイオードにテラヘルツパルスを照射することで発振が誘起されること、またその出力に高調波成分が含まれることを見出した。

2021年第68回応用物理学会春季学術講演会

wireless communications and development of practical packeges using resonant tunneling diodes

yosuke nishida

300 ghz帯の共鳴トンネルダイオードを用いた高速無線通信と用途に応じたパッケージ開発について紹介する。

2021年電子情報通信学会 総合大会

prospects for long-range terahertz imaging techniques

li yi（osaka university）

テラヘルツ波を用いた長距離(メートル級)イメージング技術について、関連するハードウェア、ソフトウェアにおける近年の進展および問題点を述べる。また、筆者らが行っている研究の一端を紹介する。

2021年電子情報通信学会 総合大会

two-dimensional imaging system using a single resonant tunneling diode transceiver

ryoko mizuno（osaka university）

単一の共鳴トンネルダイオードにおける送受信同時動作を利用したテラヘルツ帯イメージングシステムを提案し、実証した。

2021年電子情報通信学会 総合大会

fumiya nagasawa

scientific reports, volume: 11, issue: 1, jan. 2021, pp. 1497

hiroaki matsumori (名古屋工業大学)

aip advances, volume: 11, issue: 015338, jan. 2021, pp. 1-4

shunsuke akasaka

sensors and actuators b: chemicalvolume: 327 , issue:1 , jan.2021 , pp. 128932-128939

ageing monitoring of gan transistores using recurrent neural networks

florian chalvin

developping a method to track gan transistor degradation over time with recurrent neural networks. from measurements easily obtained during the normal operation of the transistor we can detect if the behavior is standard or if there is an anomaly. this method should enable live monitoring of device health.

issm2020

imaging applications with a single resonnant tunneling diode transceiver at 300ghz band

li yi（osaka university）

we employed a single resonant tunneling diode as both a transmitter and a receiver simultaneously, and demonstrated its impact in terahertz imaging applications.it leads to simplify terahertz imaging systems.

2020 international topical meeting on microwave photonics

influences of device parameters variability on current sharing of parallel-connected sic mosfets

yohei nakamura

influence of device parameter variation on current sharing between sic mosfets connected in parallel has been studied. from the simulation results, we reveal the device parameters which mainly affetct the static and dynamic current sharing behavior of the devices. we also evaluate the effect of the current sharing mismatch on energy loss for each device.

ats2020 (asian test symposium 2020)

pore size and shape dependences on quasi-static tensile characteristics of sintered silver films

keisuke wakamoto

the presentation reveals the pore size and shape dependences on sintered silver mechanical durabilities. from stress-strain results, uniform crystal structure make sphere and small  pore shape. in terms of thermal cycle reliability using sintered silver materials, uniform structure with small and sphere pore state is essential.

mnc2020

マシンヘルスモニタリングシステムにおける、mems型加速度センサの自己診断

takashi naiki

a method to diagnose whether the accelerometer itself is in a state of mechanical deterioration by statistically examining the output data from the accelerometer while the machine health monitoring application system is in continuous operation.

第37回「センサ・マイクロマシンと応用システム」シンポジウム（電気学会センサ・マイクロマシン部門）

anisotropic temperature distribution causing the incremental saturated drain-current observed in the i-v characteristic of the sic mosfet

shogo ogawa

the id-vd charactaristic in high-id and high-vd range of sic-mosfet shows incremental trend instead of saturated id behavior. by tcad simulation, the self-heating at measurement reproduce well this incremental trend.

ssdm2020

zn-doped gan mesa structure as a gate for normally-off algan/gan-hfet

norikazu ito

in the evaluation of the impurity level depth in zn-doped gan, it was found that zn behaves as an acceptor impurity in gan by forming the state at 0.3 ev from the top of the valence band. normaly-off operation was confirmed in an algan/gan hfet with a 0.1 μm mesa shape using zn-doped gan as the gate layer.

ssdm2020

current-and-voltage hybrid source gate driver for maximizing the switching capability of sic-mosfets

ryosuke ishido

to maximise the switching capability of sic-mosfet, we introduce a current and voltage hybrid source gate driver and design method.

wipda asia 2020

miniaturized 48 v‒12 v insulation-type dc/dc converter miniaturized by using gan transistors operating at 2-mhz switching frequency

koki sakamoto

the adoption of small qoss and small qg gan transistors was found to be a useful option to solve both the miniaturization and high power conversion efficiency of switching power supplies. isolated 48 v-12 v llc converter with a switching frequency of 2 mhz and 100 w class was fabricated, and the maximum power conversion efficiency reached 95.3%.

wipda asia 2020

research activities to maximize the capability of new power devices

ken nakahara

the basic characteristics of the latest generation of rohm's sic-mosfets are presented and compared with the current generation of devices in production. on the other hand, it is often assumed that better power device characteristics improve power-circuit performace, but it is not that simple. for better system-level performance, our researches of power applications and the related simulations are also presented.

wipda asia 2020

the influence of mechanical property on the heat-cycle reliability of sintered silver die attach

keisuke wakamoto

this research investigates how the mechanical properties of sintered silver (s-ag) as a die attach material influence its heat-cycle reliability. s-ag mechanical fatigue life was 500 times under elastic stress. to investigate the correlation between fatigue mechanical test and thermal shocked test (tst), we performed tst with different temperature patterns. from tst results, higher tst gives faster degradation of s-ag.

ieee　ispsd2020

study on degredation mechanism of sintered silver mechanical joint

yuga kumakiri（kyoto university of advanced science）

銀焼成を用いたモジュールの熱信頼性評価技術が求められている。
しかしながら、熱信頼性試験は、評価期間に約3ヵ月を有することから、開発スピードのボトルネックになっている。本発表では、機械負荷試験を用いた信頼性加速試験について発表している。銀焼成接合層部に、せん断応力を負荷できるセットアップにすることで、熱信頼性試験後の亀裂破壊を再現することに成功した。

日本機械学会2020年度年次大会

quasi-static tensile and fatigue tests of sintered silver film

shingo kamimachi（kyoto university of advanced science）

銀焼成を用いたモジュール化へ向けて、その機械特性を把握することが重要である。
本発表では、銀焼成と銀箔の引張機械特性を比較している。銀焼成は銀箔と比較すると、常温時に高強度であるが、疲労破壊しやすい材料であることが分かった。

日本機械学会2020年度年次大会

temperature dependency on thermal reliability test result by sintered silver interconnection

keisuke wakamoto

高熱伝導・耐熱な接合が可能になる銀焼成材は将来接合着技術として期待される。この材料を用いたモジュール化には、熱信頼性試験をクリアする必要がある。本発表では、銀焼成の引張機械特性を取得し、あえて温度帯を低温側と高温側に分けて熱信頼性試験を実施した。結果から、高温側での機械特性が熱信頼性試験上、重要であることを明かした。

日本機械学会2020年度年次大会

pulsed injection locking dynamics of resonant tunneling diode terahertz oscillators

takashi arikawa（kyoto university）

第81回応用物理学会秋季学術講演会

development of lidar system with photonic crystal laser

wataru kunishi

第81回応用物理学会秋季学術講演会

flatbands in millimeter-scale twisted bilayer graphene

keiju sato

twisted bilyaer graphene can be mocified the energy band structure by changing the rotation angle. especially, the 1.1degree called as a magic angle can be shown the superconductivity. however, the next challenge is to obtain big scale (millimeter-scale) tbg samples. this research was shown to obtain it with using transfer graphene after annealing.

応用物理学会

rotation angle control of multilayer graphene on sic (000-1)

wataru norimatsu

the method to control graphene angle on c face in sic(000-1) is not performed, so this research is challenging to control it.

応用物理学会

development of long term stable platinum microheater

yurina amamoto

第81回応用物理学会秋季学術講演会

development of practical terahertz package for resonant tunneling diode oscillators and detectors

kazuisao tsuruda

we have devloped the world's first small general-purpose plcc package and a high-gain antenna integrated package for terahertz devices. there are promising as a high-frequency package form that are functional and can be mass produced.

ieee rfit2020

keisuke wakamoto

materialsvolume: 13 , issue:4061 , sep.2020

tomohiro otsuka (tohoku university)

scientific reportsvolume: 10 , issue:1 , sep.2020 , pp. 15421

naoaki tsurumi

the journal of adhesionvolume: 0 , issue:0 , aug. 2020 , pp. 1-25

yohei nakamura

ieee transactions on power electronics, volume: 35, issue: 3, jul.2020, pp. 2950 - 2958

junichi kashiwagi

ieee access, volume:8, issue:28,may 2020, pp.101915-101922

taketoshi tanaka

ieice transactions on electronics
volume: e103.c , issue: 4 , apr. 2020 , pp. 186-190

semi-theoretical prediction of turn-off surge voltage in a sic mosfet power module with an embedded dc-link decoupling capacitor

tatsuya miyazaki

this paper presents a semi-theoretical method for predicting the turn-off surge voltage (vsurge) in double-pulse test (dpt) using a power module (pm) with sic mosfets and an embedded dc-link decoupling capacitor. in this scheme, multiple kirchhoff’s laws-based equations are simultaneously solved, and drain-source voltage and drain current are mathematically expressed. this calculation process is semi-theoretical, and sufficiently predicts the vsurge observed in dpt performed under various conditions.

apec2020

efficient of the number of dbr layers on m² of photonic crystal lasers

wataru kunishi

フォトニック結晶ldに置いて、裏面dbr層の周期数を増やす(反射率を大きくする)ことでビーム品質の改善が得られることを見出した。dbr層を透過した光が不要な乱反射を招き、ビーム品質を低下させる可能性があり、それを抑制した結果であると考えられる。

第67回応用物理学会春季学術講演会

modeling of switching device and simulation of power converter, and its trends

yuta okawauchi

ワイドバンドギャップ半導体デバイスのモデリング手法とその適用事例，さらに電力変換器の高周波化に伴うスイッチング素子周辺のモデリング手法について最新動向を紹介する。

令和2年電気学会全国大会

effect of the sintered silver die attach thickness in hert-cycle reliability

maiko hatano

第34回　エレクトロニクス実装学会講演大会

the influence of sintered silver mechanical property on the heat cycle reliability life time

keisuke wakamoto

銀焼成の引張疲労機械特性を常温領域で取得し、ストレスと、破断寿命の関係を得た。さらに銀焼成材を用いた接合体を-60℃から60℃の範囲で温度サイクル試験を実施した。超音波探傷像によって接合評価すると700サイクル後も接合劣化しておらず、引張疲労機械特性の結果と相関がとれていることを確認した。

第34回　エレクトロニクス実装学会講演大会

yohei nakamura

ieee electron device letters
volume: 41, issue: 4 , apr. 2020 , pp. 581 - 584

dynamic on-state resistance measurement of gan-hemt by double pulse test

ryosuke ishido

demonstrate the dynamic on-state resistance of gan-hemt and estimate inpact of loss of devices.

icmass2019

modeling of sic umos chip and its application to power module

hiroyuki sakairi

the modeling method developed in sic dmos was applied to the sic umos and its versatility was verified. the model was also evaluated by comparing the switching waveforms fo a power module with sic umos chip. as a result, the sic umos model reproduced the measurement data with high accuracy as well as the sic dmos.

international conference on materials and systems for sustainability

mechanical property of nano porous sintered silver: toward reliability estimation

keisuke wakamoto

the fatigue mechanical property of sintered silver plays a critical role to estimate the reliability of systems. the tensile fatigue test is performed for the sintered silver with p=5% and the bulk silver. the fatigue lifetime of the silver films is shorter than that of the bulk silver one.

material science conference 2019

hironori okumura (筑波大学)

japanese journal of applied physics, volume: 58, number: 12, pp.120902

a gate driver maximizing the switching capability of sic mosfets

yusuke nakakohara

this study report that high speed switching gate drive circuit for sic mosfets. the provided gate drive circuit adapted subsidery capacitor in order to add gate voltage, enables increase gate current. this allows fast charge and discharge and reduced switching losses. this study confirmed that the provided gate drive circuit reduce switching loss compared to conventional one.

icscrm2019

dynamic measurement method to extract high voltage and high current i-v characteristics of sic mosfet with reduced self heating

yohei nakamura

a novel measurement method to extract high voltage and high current i-v characteristics (hvhc i-v)of sic mosfet is proposed in this paper. the method could extract the hvhc i-v with extremely reduced self heating of the device. by using the method, we can measure higher voltage and current i-v characteristics than those extracted by the conventional method. it is possible for us to measure the hvhc i-v of the next generation sic mosfet, whose rated volatge and current is more than those of the conventional device.

icscrm2019

switching behavior based method to estimate the intrinsic gate resistance of a transistor by using gate plateau voltage

tatsuya yanagi

the internal gate resistance of sic mosfet effects its switching behavior larger than si devices because it can switch at high speed with low external gate resistance. however, the convention mesurement method of internal gate resistance is not accurate. then, we devised the new measurement method of it at switching operation by the switching waveforms.

ecce2019

tensile mechanical fatigue properties of sintered porous silver films

keisuke wakamoto

the tensile mechanical properties of sintered silver materials depend on its porosity rate. however, the fatigue mechanical properties of sintered silver materials are still unclear. the fatigue tests were performed with sintered silver and bulk silver films. sintered silver films were fabricated under high process pressure (60mpa) and the porosity rate is 5%(±1%). from tensile fatigue tests, the fatigue tensile strength of sintered porous silver films tends to decrease in comparison with bulk silver films.

日本機械学会

shunsuke akasaka

"sensors and actuators a: physical
volume: 296 , issue: 1 , sep. 2019 , pp. 286-291"

a study of adhesion interface about die bonding structure using conductive adhesives

naoaki tsurumi

第57回日本接着学会年次大会

observation of surface morphology change of pzt thin film during dry etching process

tomohiro date

ロームの高度な分析・解析技術により、pzt薄膜のドライエッチング中に起こる形態変化がpztの結晶方位が変動する現象に起因することを突き止めた。

第36回強誘電体応用会議(fma)

research for maximizing the potentials of wide bandgap semiconductor power devices

ken nakahara

sic and gan power devices show excellent capabilities as switching elements in power supplies, but the technologies must be simultaneouly developed to make them full-fledged. in this lecture, rohm explaines the new power appliciations enabled only by sic and gan devices, the simulation techniques to design then and how to solve inevitably accompanied noise issues.

先端パワー半導体分科会第14回研究会

measurement scheme to model an sic mosfet for simulating its switching behaviors

tatsuya yanagi

the precise modeling of sic mosfets are difficult by means of conventional modeling method of si devices because of the device characteristics. then, we invented the new modeling method for sic mosfets which can reproduce its switching behavior precisely.

pcim2017

keisuke wakamoto

japanese journal of applied physics volume: 58 , number sd , jun. 2019 , sddl08-1-5

terahertz fibre transmission link using resonant tunnelling diodes integrated with photonic-crystal waveguides

xiongbin yu（osaka university）

electronics letters volume: 55 , issue: 7 , apr. 2019 , pp. 398-400

thermal warpage behavior analysis of semiconductor package of semiconductor packaging structure

kento kariya

20th annual international conference on thermal, mechanical and multi-physics
simulation and experiments in microelectronics and microsystems (eurosime2019)

a high efficiency 3-phase 400v 15kw power inverter using sic mosfets and trans-linked topology

tatsuya miyazaki

a 3-phase15kw using sic mosfets and trans-linked topology achieved maximum efficiency of 99.2%, and verified the benefit of combining sic mosfet with trans-linked technology.

apec2019

iot application from the viewpoint of electronic devices and potential of energy harvesting

yoshiaki oku

2019年電子情報通信学会総合大会

high speed gate circuit for sic-mosfet utilizing capacitor

yusuke nakakohara

this study report that high speed switching gate drive circuit for sic mosfets. the provided gate drive circuit adapted subsidery capacitor in order to add gate voltage, enables increase gate current. this allows fast charge and discharge and reduced switching losses. this study confirmed that the provided gate drive circuit reduce switching loss compared to conventional one.

平成31年電気学会全国大会

a study on hybrid-source gate drive circuit using inductor for sic-mosfet

yuta okawauchi

a current and voltage hybrid-source gate drive circuit for sic-mosfet reduced the turn-on and turn-off lossess by 50% and 35%, respectively.

平成31年電気学会全国大会

yongpan liu(tsinghua university)

ieee journal of solid-state circuits volume: 54 , issue: 3 , mar. 2019 , pp. 885-895

a study of adhesion interface about die bonding structure with conductive silver paste

naoaki tsurumi

ieee cpmt symposium japan 2018

influence of porosity on tensile mechanical properties of sintered porous silver films

keisuke wakamoto

this paper investigates the porosity-dependent tensile mechanical properties of porous 8-10 μm thick silver films. the silver films are fabricated by pressure press, the variety of which changes the porosity (p) ranging 5% to 25%. p is determined by use of scanning electron microscopy cross-section images of the films. stress-strain (s-s) curves are obtained by tensile tests performed for the porous and bulk silver films.breaking strain and ultimate tensile strengh decrease almost linearly with increase of p.

mnc 2018, 31st international microprocesses and nanotechnology conference

power application research to utilize the full potential of wide band-gap power semiconductor devices

ken nakahara

sic and gan power devices show excellent capabilities as switching elements in power supplies, but the technologies must be simultaneouly developed to make them full-fledged. in this lecture, rohm explaines the new power appliciations enabled only by sic and gan devices, the simulation techniques to design.

先端パワー半導体分科会第5回講演会

development of resonant tunneling diodes for terahertz applications

jaeyoung kim

workshop: introduced rtd devices for thz communication and sensing. with comparison with other terahertz device, rtds are compact and power-efficient.

apmc2018

tensile mechanical properties of sintered porous silver films

keisuke wakamoto

the mechanical properties of die-attach materials are a decisive factor in determing the reliability of the system. sintered porous silver is attracting much attention as a next-generation die-attach material,however still do not clalify the mechanical properties. authors prepared thin sintered silver and bulk silver films.sintered silver films were fabricated under various pressure. from tensile tests, sintered porous silver films exhibit brittle characteristic in comparison with silver films and show high strength under high process pressure.

日本機械学会

hiroyuki sakairi

ieee transactions on power electronicsvolume: 33 , issue:9 , sep.2018 , pp. 7314-7325

application of pzt thin film devices to realize iot society

yoshiaki oku

a number of iot applications are rapidly growing. among others, smart factory, smart infrastructure and digital medicine/health are major iot markets. rohm also succeeded in demonstration of healthcare monitoring utilizing non-volatile pzt devices. the essentials for iot society and rohm’s device applications of pzt thin film were described.

the 12th japan-korea conference on ferroelectrics (jkc-fe12)

a small signal ac model using scalable drain current equations of algan/gan mis enhancement hemt

hitoshi aoki (teikyo heisei university)

a scalable drain current model and a small-signal ac model have been developed for algan/gan mis hemts with embedded source field plate. the model was found to reproduce the device characteristics well by comparing the id-vds, id-vgs, s11and h21 characteristics of the device.

rf-ic2018

a trans-linked 5-kw inverter using sic mosfets to achieve fan-less operation

tatsuya miyazaki

a trans-linked 5kw interleaved inverter using sic mosfets drastically reduced both tansistor loss and reactor losses, resulting in high efficiency over 99% and fanless operation.

pcim2018

electro-thermal simulation for predicting the temperature of sic dies in the power module of a high frequency operating power converter

yohei nakamura

the accurate electro-thermal simulation is presented by using a new sic die model to predict the power loss and temperature of sic mosfet dies in a power module. the new model incorporates a temperature dependent i-v model and body diode model which is dependent on the gate-voltage. the simulation using the model yields an accurate power loss and temperature estimate of the sic module in a buck converter.

pcim2018

s-parameter based simulation modeling a power module independent of measurement data

junichi kashiwagi

s-parameter based simulation model for power module (pm) except for the semiconductor chips was created with electromagnetic simulation. this pm model was combined with the chip model in order to build the model of the whole structure. as a result of verifying the model by the double pulse test, the simulation waveforms which reproduce the measurement results well were obtained.

pcim2018

a newly developed high performance pzt thin films by using sputtering and sol-gel hybrid method for piezo-mems device

tomohiro date

we have proposed a new hybrid structure of the pzt film which we made by sol-gel method of construction on the pbtio3 seed layer made by rf magnetron sputtering. these hybrid pzt films showed high (100)/(001) orientation and had high breakdown voltage.

2018 isaf-fma-amf-amec-pfm joint conference (ifaap2018)

application of pzt thin film devices to realize iot society

yoshiaki oku

rohm has developed pzt thin film devices, such as non-volatile ferroelectric memory, highly-sensitive sensors, highly-accurate actuators, high-speed space light modulators and ultra-low-power-consumption non-volatile flip-flop devices so far. rohm also succeeded in demonstration of healthcare monitoring utilizing non-volatile pzt devices (memory and logic). in this presentation, rohm’s device applications of pzt thin film were described.

2018 isaf-fma-amf-amec-pfm joint conference (ifaap2018)

junichi kashiwagi

ieee transactions on circuits and systems ii: express briefs volume: 66 , issue: 1 , jan. 2019 , pp. 101-105

luong duy manh (osaka university)

ieee transactions on terahertz science and technology volume: 8 , issue: 4 , jul. 2018 , pp. 455-464

sic-mosfet用電流電圧ハイブリッド形高速ゲート駆動回路の基礎検討

yuta okawauchi

this report proposes a current and voltage hybrid-source gate drive circuit for sic-mosfet.the simulation studys demonstrated that the proposed circuit stabilized gate-source voltage and reduced switching loss.

平成30年電気学会全国大会

circuit simulation of a silicon-carbide mosfet considering the effect of the parasitic elements on circuit boards by using s-parameters

tatsuya yanagi

the high speed switching of sic mosfet is affected by the parasitic elements of circuit board. therefore, we analyzed the impact of stray capacitance in circuit board on the switching behavior and tried circuit simulation of the effect by use of precise model and electromagnetic simulation results of circuit board.

apec2018

tatsuya miyazaki

ieee transactions on industrial electronics volume: 65 , issue: 12 , dec. 2018 , pp. 9429-9437

resonant tunneling diodes for thz applications

jaeyoung kim

present the recent advance of rtd-based terahertz devices. based on a well-defined equivalent circuit model, circuits like mixer, detector, and oscillators have been integrated.

alt 2017

imc formation and suppression at the interface of high pb containing solder / cu frame

takuji maekawa

エレクトロニクス実装学会 mes2017

application of pzt piezo-electronic thin film

yoshiaki oku

iot社会におけるpztデバイスの位置付けについて述べ、ロームのpztデバイス技術（メモリからセンサ/アクチュエータ）を概観した。最近の取組み事例として、「不揮発ロジックデバイス」と「ピエゾmemsデバイス」を紹介した。

日本ゾル-ゲル学会第15回討論会

seigo mori

ieee transactions on electron devices volume: 64 , issue: 10 , oct. 2017 , pp. 4167-4174

800 v three-phase llc series resonant dc/dc converter using sic mosfets

yusuke nakakohara

this study report that a three-phase, 5-kw llc series resonant dc/dc converter utilizing sic mosfets. the high-break down voltage of sic mosfets, enables increasing the input voltage up to 800 v. around 160khz switchig frequency successfully reduces the volume of isolation transformers. current-balancing transformers among each phases effectively suppress a peak current from arising in the circuit and contributed that miniaturizes the input and output capacitances. the proposed power supply weighs 1.55 kg with dimensions including a width of 18 cm, a length of 12 cm, and a height of 12.5cm. the conversion efficiency of the converter reaches 98.1% at 5-kw operation.

pcim europe 2017

kazuma okamoto (osaka university)

journal of infrared, millimeter, and terahertz waves, volume: 38, issue: 9, may.2017, pp. 1085-1097

taketoshi tanaka

physica status solidi (a) volume: 214, issue: 8 , aug. 2017

thermoelectric enhancement in the two-dimensional electron gas of algan/gan heterostructures

kazuya nagase

14th european conference on thermoelectrics

development of mems sensors for iot society

yoshiaki oku

本講演では、iotにおけるセンサの重要性を示し、memsセンサ、及びiot/ワイヤレスセンサネットワークについて述べ、更にはアプリケーション開拓に向けた検証としてのセンサソリューションについても述べた。

2016年電子情報通信学会ソサイエティ大会シンポジウム

上面駆動型誘電エラストマーアクチュエータの駆動評価

yoshinori tanaka

第34回日本ロボット学会学術講演会

influences of magnetic core materials to power inductors fabricated by silicon technologies

naoaki tsurumi

平成28年電気学会基礎・材料・共通部門大会

sebasitian diebold (osaka university)

ieee transactions on terahertz science and technology volume: 6 , issue: 5 , sep. 2016 , pp. 716-723

terahertzsensing based on photonic crystal cavity and resonant tunneling diode”,progress in electromagnetics research symposium

kazuisao tsuruda

progress in electromagnetics research symposium 2016 china

piers 2016 china

sic-fet chip model to simulate its switching behaviors in high voltage and current region

hiroyuki sakairi

until now, the transientcharacteristics of circuit simulations using the sic device model have not been consistent. since emc must be considered when using sic devices, it is important to reproduce their transient characteristics. therefore, we have developed a novel sic devie model by measureing the id-vds characteristics with the high-voltage and high-current region and the on-state capacitance of the sic mosfet to reproduce the transient characteristics. as a result the novel sic device model successfully reproduce the switching taransient waveform with high accuracy.

第29回回路とシステムのワークショップ

iotに向けたセンサ、センサネットワークからヘルスケアまで

yoshiaki oku

iot世界においては、トリリオンセンサに代表されるように大量のセンサがネットワークでつながり、暮らしの省エネから快適性・安全性を高めていく。本講演では、各種センサとセンサネットワークへの取り組み、ヘルスケアに必要な常時モニタリングについて紹介した。

日本学術振興会第166委員会研究会

shunsuke akasaka

sensors and actuators b: chemical
volume: 236 , issue: 29,june 2016 , pp. 499-505

demonstration of a robot finger using dielectric elastomer actuator

yoshinori tanaka

第25回日本mrs年次大会

self-sustained oscillation in half bridge circuit of silicon carbide devices with inductive load

tatsuya yanagi

the self-sustained oscillations are sometimes obserbed when sic mosfets switch at high speed in the half bridge configuration. the oscillation is regard as nonlinear self-excited oscillation as a result of its device characteristics. we tried to analyze it from the aspects of device characteristics of mosfet and trajectory of the oscillation in the i-v plane.

nolta2015

prof. tadao nagatsuma (osaka university)

ieee journal of quantum electronics volume: 52 , issue: 1 , jan. 2016

kazuisao tsuruda

optics express volume: 23 , issue: 25, 2015 , pp. 31977-31990

design and integration of power inductor using silicon technology

yutaka sawai (presenter:naoaki tsurumi)

電気学会マグネティックス研究会

yusuke nakakohara

ieee transactions on industrial electronics volume: 63 , issue: 4 , apr. 2016 , pp. 2103-2110

terahertz-wave integrated circuits based on photonic crystals

kazuisao tsuruda

progress in electromagnetics research symposium 2015 czech