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検索詳細上杉 晃生大学院工学研究科 機械工学専攻助教
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■ 論文- Institute of Electrical Engineers of Japan (IEE Japan), 2023年01月, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 143(1) (1), 13 - 18
- Abstract The effect of surface potential on the carrier mobility and piezoresistance of core–shell silicon carbide nanowires (SiC NWs) was investigated to realize small and sensitive SiC-microelectromechanical systems sensors. The p-type cubic crystalline SiC (3C-SiC) NWs were synthesized via the vapor–liquid–solid method and coated with silicon dioxide (SiO2) or aluminum oxide (Al2O3) dielectric shells to form core–shell structured NWs with different surface potentials. Four-point bending devices (FBDs) with a field-effect transistor (FET) configuration integrating a single core–shell 3C-SiC NW as the FET channel were fabricated to apply an additional electric field and strain to the core–shell 3C-SiC NWs. The fixed oxide charge densities of the SiO2 and Al2O3 shells showed positive and negative values, respectively, which were equivalent to electric fields of the order of several hundred thousand volt per centimeter in absolute values. In the core–shell 3C-SiC NWs with originally low impurity concentrations, the electric field induced by the fixed oxide charge of the shells can determine not only the electrical conduction but also the charge carriers in the NWs. Bending tests using the FBDs showed that the piezoresistive effect of the SiO2-coated NW was almost the same as that of the as-grown 3C-SiC NW reported previously, regardless of the gate voltage, whereas that of the Al2O3-coated NW was considerably enhanced at negative gate voltages. The enhancement of the piezoresistive effect was attributed to the piezo-pinch effect, which was more pronounced in the NW, where the carrier density at the core–shell interface is enhanced by the electric field of the dielectric.IOP Publishing, 2022年09月, Nanotechnology, 33(50) (50), 505701 - 505701研究論文(学術雑誌)
- Various nanostructures for single-molecule surface-enhanced Raman spectroscopy (SERS) have been fabricated through a random aggregation process using nanoparticles that can stochastically generate multiple hotspots in the laser spot. This leads to multiple molecule detection. In this study, a single gold nanoparticle (AuNP) dimer with a single hotspot was fabricated in a laser spot controlling the position and orientation on a silicon substrate using a nanotrench-guided self-assembly. The Raman peaks of deoxyribonucleic acid (DNA) were dynamically observed, indicating a single DNA oligomer detection composed of adenine, guanine, cytosine, phosphate, and deoxyribose.2022年01月, Optics Letters, 47(2) (2), 373 - 376[査読有り]研究論文(学術雑誌)
- Microresonator-based optical sensing has been reported to achieve a high measurement resolution of near-infrared light intensity. The light intensity was measured from the resonant frequency shift with the thermal stress of a silicon doubly clamped beam. In this study, the beam length and vibration amplitude were considered as parameters for improving the measurement resolution. This study investigates the effect of these parameters on the sensitivity (resonant frequency shift per light intensity) and the quality factor (Q factor) to estimate the measurement resolution, considering the thermomechanical noise as the fundamental limitation. The result of the measurement indicated that the longer the resonator, the greater the shift in the resonant frequency. The Q factor is considered to be constant regardless of the resonator beam length. Although the vibration amplitude was increased until nonlinear vibration occurred, no change in the sensitivity and Q factor was observed. The light intensity measurement resolution was calculated using a theoretical equation based on the experimental tendencies. The device with the longest beam length of 800 µm and the gold nanostructured absorber had the highest resolution. The light intensity measurement resolution was improved with a longer beam length and larger vibration amplitude.2022年, Microsystem Technologies[査読有り]研究論文(学術雑誌)
- The widespread of near-infrared spectroscopes in the consumer field is expected to create new demand, such as the detections of fruit and vegetable rot and the easy measurement of the amount of water in the skin. Conventional cooled photodiodes using compound semiconductor materials such as InGaAs have problems with cost reduction and miniaturization. Therefore, we proposed an electrostatic Si microresonator device for the realization of a near-infrared optical sensor. This device measures the resonance frequency shift caused by the thermal stress generated in the resonator due to light absorption depending on the light intensity. The purpose of this study is to apply the device to near-infrared spectroscopy of water as a photodetector. We proposed an evaluation method based on a theoretical equation and confirmed that the device could detect the near-infrared absorption spectrum of water. The measurement results of the developed device matched well with that of the commercially available photodiode intensity sensor. In the future, it is expected that a compact near-infrared spectrometer with high sensitivity and low cost will be realized by arranging devices that integrate absorbers with different wavelength dependencies.2021年12月, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 104(4) (4)[査読有り]
- Institute of Electrical Engineers of Japan (IEE Japan), 2021年09月, 電気学会論文誌 E, 141(9) (9), 321 - 326[査読有り]
- The Optical Society, 2021年08月, Journal of the Optical Society of America B[査読有り]研究論文(学術雑誌)
- IOP Publishing, 2021年05月, Japanese Journal of Applied Physics, 60(5) (5), 055502 - 055502[査読有り]研究論文(学術雑誌)
- IOP Publishing, 2021年03月, Nano Express, 2(1) (1), 010032 - 010032[査読有り]研究論文(学術雑誌)
- IOP Publishing, 2021年02月, Journal of Micromechanics and Microengineering, 31(2) (2), 025009 - 025009[査読有り]研究論文(学術雑誌)
- IEEE, 2021年01月, 2021 IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS)[査読有り]研究論文(国際会議プロシーディングス)
- Elsevier BV, 2020年11月, Sensors and Actuators A: Physical, 315, 112337 - 112337[査読有り]研究論文(学術雑誌)
- © 2020 The Japan Society of Applied Physics. In this study, we investigated the effect of the resonator beam shape on the thermal stress and the resonance frequency change when providing heat to the resonator beam by near-infrared laser irradiation. This investigation provides crucial data for optical and heat sensing application using microresonators. The microresonator beam with an optical absorber for near-infrared region was fabricated, varying the numbers of beams and corners. When irradiating the optical absorber with a laser, the resonant frequency decreased. It is because the photothermal effect provides compressive stress in the beam, resulting in resonant frequency decrease. The resonant frequency change rate increased with decreasing the number of beams. According to the analytical results, we confirmed that the analytical thermal stress determined the resonant frequency change rate in the same beam length. The corner remarkably decreased the resonant frequency change rate. The straight beams bend to the orthogonal direction by the thermal expansion of another straight part of the beam, resulting in deformation of the beam in the axial direction. Therefore, the reaction force and compressive stress in the axial direction reduces.2020年, Japanese Journal of Applied Physics, 59(SI) (SI)[査読有り]研究論文(国際会議プロシーディングス)
- © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Near-infrared (NIR) imaging has been used for nondestructive and non-contact inspections in various areas, such as food and medicine inspections and medical diagnoses. The short-wavelength infrared light (SWIR) sensor currently used requires a Peltier cooler and a diffraction grating spectroscope owing to its detection principle. Thus, realizing a low-cost and miniaturized SWIR imaging device remains challenging and has limitations for practical applications. In this study, we propose a bolometer-type detector element fabricated using a silicon-on-insulator (SOI) wafer as a low cost and miniaturized SWIR image sensor element. We adopted gold (Au) nanowire grating structures coated with silicon as wavelength-dependent SWIR absorbers and aimed at wavelength-selectivity imaging without using a spectroscope. A device was designed and fabricated with Au nanowire grating structures on a doubly clamped Si beam using microelectromechanical system (MEMS)) technology. The electrical characteristics of the device were measured depending on device temperature and SWIR irradiation intensity. It was found that electrical resistance decreased linearly with increasing device temperature and SWIR irradiation intensity (wavelength at 1530 nm), as semiconductors have negative temperature coefficients of resistance. The results show similar trends from both finite element method (FEM) analysis and theoretical calculation. The resistances at wavelengths ranging from 1530 to 1565 nm at 5 nm increment were evaluated. It was confirmed that absorber-integrated bolometer device enabled wavelength-dependent response of the resistance according to the absorption spectrum.2020年, Microsystem Technologies, 27(3) (3), 997 - 1005[査読有り]研究論文(学術雑誌)
- 一般社団法人 電気学会, 2020年, 電気学会論文誌E(センサ・マイクロマシン部門誌), 140(4) (4), 72 - 78, 日本語
For applications of plasmonic structures to high performance sensors in the near-infrared region, the structures require narrowband absorption peaks, good controllability of absorption peak position, and easy fabrication process. Multiple patterns with different absorption peaks should be integrated on the same substrate. In addition, polarization independence is desired for cost reduction and miniaturization of devices. In this study, we fabricated the Si-deposited gold nano-grating structures, the wire and concentric ring structures. Then their absorption spectra were evaluated. The peak wavelength shifted to longer wavelength with increasing the pitch of the grating structure and the thickness of Si. It was revealed that the peak was greatly shifted changing the thickness of Si. In the wire structures and the concentric ring structures, polarization dependence and polarization independence of peak absorption were observed, respectively. By using the Si-deposited gold nano-grating structures, wide control of the peak wavelength was realized in the near infrared region.
[査読有り] - This study evaluated the mechanical properties and piezoresistivity of core-shell silicon carbide nanowires (C/S-SiCNWs) synthesized by a vapor-liquid-solid technique, which are a promising material for harsh environmental micro electromechanical systems (MEMS) applications. The C/S-SiCNWs were composed of a crystalline cubic (3C) SiC core wrapped by an amorphous silicon dioxide (SiO x ) shell; however, TEM observations of the NWs showed that hexagonal polytypes (2H, 4H , and 6H) were partially induced in the core by a stacking fault owing to a Shockley partial dislocation. The stress-strain relationship of the C/S-SiCNWs and SiC cores without an SiO x shell was examined using MEMS-based nanotensile tests. The tensile strengths of the C/S-SiCNWs and SiC cores were 7.0 GPa and 22.4 GPa on average, respectively. The lower strength of the C/S-SiCNWs could be attributed to the SiO x shell with the surface roughness as the breaking point. The Young's modulus of the C/S-SiCNWs was 247.2 GPa on average, whereas that of the SiC cores had a large value with scatter data ranging from 450 to 580 GPa. The geometrical model of the SiC core based on the transmission electron microscopy observations rationalized this scatter data by the volume content of the stacking fault in the core. The piezoresistive effects of the C/S-SiCNW and SiC core were also evaluated from the I-V characteristics under uniaxial tensile strain. The gauge factor of -30.7 at 0.008 ϵ for the C/S-SiCNW was approximately two-times larger than that of -15.8 at 0.01 ϵ for the SiC core. This could be caused by an increase of the surface state density at the SiO x /SiC interface owing to the positive fixed oxide charge of the SiO x shell.2019年04月, Nanotechnology, 30(26) (26), 265702, 英語[査読有り]研究論文(学術雑誌)
- MANIPULATION OF BIOMOLECULES INTO NANOGAP BY PLASMONIC OPTICAL EXCITATION FOR HIGHLY SENSITIVE BIOSENSINGThis paper demonstrates the manipulation of DNA oligomers with 16 adenine molecules using plasmonic nanogap structure. The optical excitation caused plasmonic dielectrophoresis or/and thermophoresis of molecules to the nanogap due to huge gradient of an electric field. We confirmed the single-molecule electrical measurement using the nanogap electrodes irradiated by a He-Ne laser. We considered that the DNA oligomers were transported to the nanogap resulting in conductance change. We classified the changes in the current as step- or spike-like signals. The histogram of the stagnation time shows the peak at around 22 ms. We were able to detect the behavior of DNA oligomers.IEEE, 2019年, 2019 20TH INTERNATIONAL CONFERENCE ON SOLID-STATE SENSORS, ACTUATORS AND MICROSYSTEMS & EUROSENSORS XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), 166 - 169, 英語研究論文(国際会議プロシーディングス)
- 金ナノ粒子二量体表面増強ラマン分光によるDNAオリゴマーの1塩基検出This paper reports a surface enhanced Raman spectroscopy (SERS) of a single-stranded DNA toward SERS-based DNA sequencing. The Raman enhancing hotspot with 1-nm nanogap in the single dimer of gold nanoparticles has a space for only single DNA oligomer and enables measurements of a single nucleobase. Optimizing gold nanoparticle size, we demonstrated the detection of a single adenine in a single DNA oligomer. The time transition of adenine and cytosine peaks reflects identification of adjacent bases in a DNA oligomer sequence, suggesting the possibility of one-by-one DNA sequencing with SERS.IEEE, 2019年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 36th, 979 - 982, 英語[査読有り]
- A parallel testing method has been proposed with integrated strain gauges based on the piezoresistive effect to shorten the testing time for investigating tensile-mode fatigue characteristics of single-crystal silicon (SCS). The method allows a high loading frequency (∼110 Hz) owing to the high stiffness of the testing system and reduces the testing time per specimen by parallelization. Five specimens were integrated on a testing chip and subjected to a pulling force simultaneously using a piezoelectric actuator. The parallel portion of the specimen was 2.5 μm wide, 22 μm thick, and 120 μm long. The strain gauge connected to each gauge part consisted of an array of five straight beams 100 μm in length and 2.5 μm in width. The oneactive-gauge bridge was used and three reference registers of identical shape were also placed in series on the chip. The strain gauges successfully monitored the force on each specimen with sufficiently low noise for testing. The five specimens on the chip fractured at the same time, showing a tensile strength of 1.5 GPa. Because of the finite stiffness of the test system, there is coupling between the integrated specimens. However, the total displacement during parallel testing was sufficiently small (∼15 μm) such that the system has the potential to operate with a loading frequency of 110 Hz for fatigue testing.2018年, SENSORS AND MATERIALS, 30(9) (9), 2143 - 2157, 英語[査読有り]研究論文(学術雑誌)
- This paper reports the tensile properties of single-crystal silicon (SCS) microstructures fully coated with sub-micrometer thick diamond like carbon (DLC) film using plasma enhanced chemical vapor deposition (PECVD). To minimize the deformations or damages caused by non-uniform coating of DLC, which has high compression residual stress, released SCS specimens with the dimensions of 120μm long, 4 μm wide, and 5 μm thick were coated from the top and bottom side simultaneously. The thickness of DLC coating is around 150nm and three different bias voltages were used for deposition. The tensile strength improved from 13.4 to 53.5% with the increasing of negative bias voltage. In addition, the deviation in strength also reduced significantly compared to bare SCS sample.Japan Society of Applied Physics, 2017年06月, Japanese Journal of Applied Physics, 56(6) (6), 06GN01, 英語[査読有り]研究論文(国際会議プロシーディングス)
- This Letter investigates the effect of crystallographic orientation on tensile fractures of silicon microstructures. Specimens 5 m wide and 5 m thick were fabricated on (100) and (110) wafers with 100, 110, and 111 tensile axes. To explore the effects of different surface orientations and morphologies, these specimens were patterned from (100) and (110) silicon-on-insulator (SOI) wafers using the Bosch process under identical fabrication conditions, while other specimens were fabricated from (110) wafers under different conditions. Tensile tests of specimens prepared under the identical fabrication conditions showed that (100) specimens had lower strength than (110) specimens along the 100 and 110 axes; the average strength decreased from 3.62 to 3.14 GPa for 110. This decrease in strength is related to differences in damage that ultimately causes fractures. While (110) specimens fractured due to fabrication damage at top corners, fractures of (100) specimens were due to pit-like defects on bottom surfaces. Since these defects were introduced during SOI bonding processes, the fractures of (100) specimens were dominated by intrinsic SOI defects rather than damage introduced during specimen fabrication processes. To realise higher-strength structures on SOI wafers, both the damage caused during fabrication and the intrinsic defects need to be controlled.INST ENGINEERING TECHNOLOGY-IET, 2015年12月, MICRO & NANO LETTERS, 10(12) (12), 678 - 682, 英語[査読有り]研究論文(学術雑誌)
- This paper reports development of a high-temperature tensile testing machine and testing of single crystal silicon (SCS) for investigation of the size effect on brittle-ductile transition temperature (BDTT). Two different-width (110) SCS specimens (120 mu m long, 5 mu m thick and 4 or 9 mu m wide) were tested in a vacuum at the temperature range from room temperature to 600 degrees C. The specimens tested at 500 degrees C and above exhibit slip, which indicated that the micrometer-sized silicon structures have lower BDTT compared to millimeter-sized ones. By investigating the temperature ranges of the slip occurrences among the differently-sized specimens including other researchers' reports, we found that the length along slip direction, i.e., thickness, might dominate the BDTT. (C) 2015 The Japan Society of Applied PhysicsIOP PUBLISHING LTD, 2015年06月, JAPANESE JOURNAL OF APPLIED PHYSICS, 54(6) (6), 06FP04, 英語[査読有り]研究論文(学術雑誌)
- SIZE EFFECT ON BRITTLE-DUCTILE TRANSITION TEMPERATURE OF SILICON BY MEANS OF TENSILE TESTINGThis paper reports the size effect on brittle-ductile transition temperature (BDTT) of single crystal silicon (SCS) using different width specimens (120-mu m long, 5-mu m thick and 4 or 9-mu m wide). The BDTT was characterized using tensile testing in a vacuum from room temperature to 600 degrees C. The fractured specimens showed that the slips were occurred at 500 degrees C and above, which indicated that the BDTT of micrometer-sized silicon decreased compared to millimeter-sized structures. By comparing the temperature ranges of the slip occurrences among the different sized specimens including other researchers' reports, we found that the length along slips-propagation direction, i.e. thickness, might dominate the BDTT.IEEE, 2015年, 2015 28TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2015), 389 - 392, 英語[査読有り]研究論文(国際会議プロシーディングス)
- This paper reports on a newly developed coarse-grained molecular dynamics simulation for epoxy-based chemically-amplified photoresist dedicated to MEMS. To analyze photoresists material properties, Kremer-Grest model (bead-spring model) with an extended angle bending potential was newly employed. A uniaxial elongation simulation and the molecular diffusion simulation were performed to analyze the dependence of an elastic modulus and a molecular permeability on the cross-linked ratio of a photoresists, since these characteristics are important for a permeable membrane made of photoresist to control biological molecules diffusion in biomedical applications. The simulated dependencies of the elastic modulus and the molecular permeability on the cross-linked ratio of photoresists showed good correspondences with the experimental results. This suggests a photoresists membrane can be used as a molecular permeable membrane with controllable permeability by varying photolithography process parameters.一般社団法人 電気学会, 2013年08月, 電気学会論文誌. E, センサ・マイクロマシン部門誌, 133(8) (8), 320 - 329, 日本語[査読有り]研究論文(学術雑誌)
- We report the effects of surface damage and crystal orientation on fracture strength of single crystal silicon (SCS) by means of tensile test using electrostatic-force grip. The specimens of three major crystal orientations fabricated from (110) SOI wafer were characterized with different surface morphologies prepared by the specimen patterning process. Our specimen patterning process was composed of Bosch process and wet etching process for surface residue removal. We changed processing time and sequence of the two processes to get different surface morphologies. As result of uni-axial tensile test of 9 types of specimens (length: 120 μm, width: 5 μm, thickness: 5 μm), i.e. specimens of 3 crystal orientations with 3 different surface morphologies, improvement of surface morphology doubled average tensile strength: e.g. < 110> strength varied from 1.8 GPa to 3.6 GPa, while average tensile strength difference among crystal orientations was less than 20 % on each fabrication conditions. The fracture surfaces mainly consisted of (111) plane. We found tensile fracture characteristics of 3 crystal orientations: in < 100> specimens the fracture origin location changed by the fabrication conditions, while < 110> and < 111> specimens respectively showed quantitative relationships between surface morphology and tensile strength common to different fabrication conditions. These results are beneficial for tensile strength prediction from surface morphology. © 2013 The Japan Society of Mechanical Engineers.2013年, 日本機械学会論文誌A編, 79(804) (804), 1191 - 1200, 日本語[査読有り]研究論文(国際会議プロシーディングス)
- The mechanical properties of an epoxy-based chemically amplified resists with various cross-linking ratios were simulated using a newly developed coarse-grained molecular dynamics simulation that employs a bead-spring model. Models with the different cross-linking ratios were created in the molecular dynamics calculation step and uniaxial elongation simulations were performed. The results reveal that the simulated elastic modulus of the resist modeled by the Kremer-Grest model with an extended angle bending potential depends on the cross-linking ratio, its dependency exhibits good agreement with that determined by nanoindentation tests. (c) 2012 Elsevier Ltd. All rights reserved.ELSEVIER SCI LTD, 2012年09月, POLYMER, 53(21) (21), 4834 - 4842, 英語[査読有り]研究論文(学術雑誌)
- We conducted uni-axial tensile test using electrostatic-force grip on thin film single crystal silicon of < 110> direction. The specimens were fabricated on (110) SOI wafer (length: 120 μm, width: 5 μm, thickness: 5 μm) and went through 3 different conditions of patterning process composed of Bosch process and wet etching process for surface residue removal. As a result, improvement of surface morphology brought increase of average tensile strength from 1.9 GPa to 3.6 GPa. SEM observation of fractured specimens suggests that, regardless of processing conditions, relationship between tensile strength and the top-view length of (110) crystal plane of specimens can be expressed with a common equation. © 2012 The Institute of Electrical Engineers of Japan.Institute of Electrical Engineers of Japan, 2012年, IEEJ Transactions on Sensors and Micromachines, 132(9) (9), 320 - 321, 日本語[査読有り]研究論文(学術雑誌)
- 2023年, 電気学会論文誌 E, 143(7) (7)モノリシック集積コアシェルSiナノワイヤ架橋構造の熱起電力評価
- 2023年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 40th金コロイド溶液濃度調整による表面増強ラマン分光の感度向上
- 2023年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 40thAl2O3エレクトレット膜被覆Siナノワイヤのピエゾ抵抗効果
- 2023年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 40thたわみを有する両端固定梁の光応答周波数変化の計算
- 2023年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 40th金ナノ粒子二量体ナノギャップ制御による表面増強ラマン分光の感度増強
- 2022年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 39th表面増強ラマン分光による単一DNAオリゴマー計測の評価
- 2022年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 39th原子層堆積Al2O3誘電膜のエレクトレット化に関する研究
- 2022年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 39thモノリシック集積コアシェルSiナノワイヤ架橋構造の熱起電力評価
- 2022年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 39th金ナノ粒子二量体を用いた表面増強ラマン分光によるメチル化アデニン1塩基計測
- 2021年, マルチスケール材料力学シンポジウム講演論文集(CD-ROM), 6thコアシェルSiCナノワイヤのピエゾ抵抗効果に及ぼすシェル表面電位の影響評価
- 2021年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 38thMACE表面ナノホールのシリコンナノワイヤ垂直成長促進効果
- 2021年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 38thコアシェル構造SiCナノワイヤの界面静電場によるピエゾ抵抗効果の制御
- 2021年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 38th電気的・光学的1分子計測に向けた金ナノ粒子二量体ナノギャップの作製・制御・評価
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 5p, 日本語マイクロ振動子のたわみ状態制御による振動型光センサの高感度化—Study on sensitivity improvement of microresonator-based optical sensor by deflection control
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 5p, 日本語高温パンチクリープ成形技術を用いた3軸力センサの開発および被覆樹脂の粘弾性特性を考慮したセンサ性能評価—Development of three-axis force sensor by 3D microstructuring using high temperature punch creep forming and sensor performance evaluation considering resin viscoelasticity
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 6p, 日本語金ナノ構造を用いた波長依存性を有するSOI型近赤外ボロメータ素子—Study on wavelength-dependent SOI-type near-infrared bolometer element using gold nanostructure
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 6p, 日本語金ナノ構造光吸収体集積静電型マイクロ振動子デバイスによる近赤外光強度センサ—Near-infrared light intensity sensing by electrostatic microresonator transducer integrated with gold nanostructure optical absorber
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 5p, 日本語近赤外吸収体を有する静電型マイクロ振動子デバイスを用いた水の分光測定—Spectroscopic measurement of water using electrostatic transducer with Near-infrared absorber
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 6p, 日本語金ナノ粒子二量体を用いたナノギャップ電極の作製とその電気的・光学的評価—Fabrication of nanogap electrode based on gold nanoparticle dimer and its electrical and optical evaluation
- 2020年10月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 37, 6p, 日本語光センシングマイクロ共振デバイスの梁長さおよび振幅が計測分解能に与える影響—Effects of beam length and amplitude on measurement resolution in optical sensing using microresonator
- 2019年11月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 36, 6p, 日本語光励起ナノギャップ電極を用いたDNAオリゴマーの光トラップおよび1分子検出—Optical trapping and single-molecule detection of DNA oligomer using optically-excited nanogap electrodes
- 2019年11月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 36, 4p, 日本語架橋成長Siナノワイヤの熱電特性評価に関する研究—Characterization of thermoelectric properties of bridged-grown Si nanowire
- 2019年11月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 36, 4p, 日本語シリコンマイクロ振動子光センサにおける共振周波数特性の形状依存性—Pattern dependency of resonant frequency response of silicon microresonator for optical sensing
- 2019年11月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 36, 4p, 日本語金ナノグレーティング構造の光吸収ピーク波長制御による高感度レーザ波長計測マイクロ振動子デバイス—Highly sensitive laser wavelength measurement using microresonator controlling absorption peak of gold nanograting
- 2019年11月, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 36, 4p, 日本語コアシェルSiCナノワイヤの電気伝導性に及ぼすシェル表面電位の影響解明—Effect of shell surface potential to electrical properties of core-shell SiC nanowire
- 2019年, センサ・マイクロマシンと応用システムシンポジウム(CD-ROM), 36th静電型マイクロ振動子トランスデューサを用いたシリコン近赤外光強度センサ
- 一般社団法人 日本機械学会, 2019年, 東海支部総会講演会講演論文集, 2019.68, 124, 日本語
- In this study, thermal oxidation is applied to SiGe MEMS resonator to investigate the effect of oxide layer on mechanical reliability of SiGe film. The resonator was designed to investigate high-cycle fatigue life of SiGe film. A SiGe cantilever beam with a notch is subjected to in-plane cyclic bending stressing at around 25 kHz by using a fan-shaped micro resonator with an electrostatic comb actuator. SiGe film having a thickness of 20 μm and a 70 at% Ge was used as a structural material of the resonator. The resonator was thermally oxidized at 600 °C for 1 hour. A submicron thick oxide film with 70 at% O, 10 at% Si and 20 at% Ge was formed. In the stress ramping test, the non-oxidized SiGe failed at a principal stress ranging from 1.5 to 2.0 GPa, whereas the oxidized SiGe fractured at a principal stress ranging from 0.9 to 1.2 GPa. The oxide layer negatively affected mechanical reliability of SiGe film.一般社団法人 日本機械学会, 2019年, 年次大会, 2019, J22311P, 日本語
- 2018年, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 35, 6p, 日本語Si薄膜被覆金ナノグレーティング構造の近赤外域光吸収スペクトル偏光依存性—Polarization dependence of near-infrared absorption spectrum of Si-deposited gold nano-grating structures
- 2018年, 「センサ・マイクロマシンと応用システム」シンポジウム論文集 電気学会センサ・マイクロマシン部門 [編], 35, 5p, 日本語VLS成長SiNW単体に対する熱電変換特性評価—Characterization of thermoelectric properties for VLS-growth SiNWs
- We report a comparison of fatigue properties of single-crystal silicon (SCS) film and polycrystalline-silicon germanium (poly-SiGe) film with Ge content of 70 at%. Fatigue property measurement was carried out using a microresonator fabricated from 20-μm-thick films and with an identical design. In order to clarify relationship between fracture deflection angles and cyclic loadings, short-term fracture properties were also evaluated using the same microresonator under ramped amplitude deflections. As a result, in short-term fracture testing, SCS specimens fractured at 60 % larger deflection angle on average, compared with that of poly-SiGe specimens. This result indicates that fracture strain of the poly-SiGe film is slightly smaller than SCS films. In fatigue testing, poly-SiGe film showed small decrease of fracture deflection angles up to 1010 cycles, while fracture deflection angle of SCS film showed 20 % decrease under 106-107 cycles and also showed similar fracture deflection angle with poly-SiGe film at 109 cycles. These results indicate that poly-SiGe film is comparable with SCS film as a structural material to design MEMS with a high-long reliability.一般社団法人 日本機械学会, 2018年, 年次大会, 2018, J2230302, 日本語
- 一般社団法人 日本機械学会, 2018年, 年次大会, 2018, J2230301, 日本語
- A tensile-mode parallel fatigue testing device with integrated shear strain gauge has been developed for reliability assessment of single crystal silicon (SCS) microstructures. We must shorten the testing time need to be shortento realize ultra-high cycle fatigue testing for ensuring the long time reliability of MEMS device. Our approach is parallel testing and high stiffness strain gauge to increase loading frequency. In this report, we introduce a design of shear strain gauge, which has improved stiffness and sensitivity. The testing device has five SCS specimens of 120 μm long, 4 μm wide and 2 μm thick, integrated with the shear strain gauge. We performed parallel tensile testing with the device fabricated from p-type silicon-on-insulator wafer and confirmed output from the strain gauges. Stress calibration with finite element analysis, theoretical calculation and digital image correlation was performed and the order of results correspond with each other.一般社団法人 日本機械学会, 2017年, 年次大会, 2017, J2210105, 日本語
- This paper reports evaluation of mechanical properties and fracture strengths of polycrystalline silicon germanium (poly SiGe) film with Ge concentrations of 46.4-87.0 at% using tensile testing and indentation test. Thicknesses of the SiGe film were 4.8-10.0 μm, depending on Ge concentrations. As a result, Young’s moduli of 110-127 GPa and 129-149 GPa were obtained from tensile testing and indentation test, respectively. The obtained Young’s moduli had a low correlation with Ge concentrations and were similar to Young’s modulus of poly Ge film. In the tensile testing, fracture strengths of the SiGe films were 1.1-1.7 GPa. Due to brittleness of the SiGe films, the obtained fracture strengths were thought to be affected by surface damage caused during device patterning.一般社団法人 日本機械学会, 2017年, マイクロ・ナノ工学シンポジウム, 2017.8, PN-113, 日本語
- We report fatigue testing of poly-silicon germanium (SiGe) film using microresonator and its fabrication process. Fatigue testing specimens of 20-μm-thick SiGe with 70 at% germanium was designed to investigate high-cyle fatigue life of SiGe film. 10-μm-wide beams with two types of notches on the specimens were subjected to in-plane bending stresses at around 25 kHz by a fan-shaped microresonator excited using an electrostatic comb actuator. Since etching process of Ge-enriched SiGe film was not fully established, processing conditions of a deep reactive ion etching (DRIE) were studied to pattern the specimens. In fatigue testing performed up to 109-1010 cycles, fatigue fractures occurred under principal stresses of 1.9-3.3 GPa. The fatigue lives of the both specimens had a large dispersion due to brittleness of SiGe, and the two types of specimens showed different fatigue strengths. The fatigue fractures started from sidewall surface damage, which indicates that scallops damage of DRIE affected the fatigue strengths and that difference of etching damage at the notches depending on the shapes might affect the fatigue strengths.一般社団法人 日本機械学会, 2017年, 年次大会, 2017, J2210204, 日本語
- This paper reports on the effect of deposition bias voltage on tensile properties of single crystal silicon microstructure fully coated by plasma CVD diamond like carbon (DLC) film. DLC film with the thickness of 150 nm was uniformly coated on silicon microstructure of 120 μm long, 4μm wide and 5 μm thick. The result shows that by increasing of bias voltage, sp2 phase and hydrogen content decreased, while sp3 phase increased. The average tensile strength of DLC coated structure shows 13.2-29.6% higher values compared to that of the bare silicon structure and the -400 V bias voltage gave the highest strength of 3.94 GPa. Moreover, the Weibull modulus increased with higher bias voltage, which indicates smaller deviations in strength.一般社団法人 日本機械学会, 2017年, 年次大会, 2017, J2210103, 日本語
- The paper reports the improvement of tensile strength of single-crystal silicon (SCS) microstructures fully coated with sub-micrometer thick diamond like carbon (DLC) film using plasma enhanced chemical vapor deposition (PECVD). To minimize the deformations or damages caused by non-uniform coating of DLC, which has high residual stress, the released SCS specimens with the dimensions of 120 mu m long, 4 mu m wide and 5 mu m thick were coated from the top and bottom side simultaneously. Three kinds of different deposition bias voltages were adopted with the thickness around 150 nm. The tensile strength improved up to 53.5% by the full coatings depending on deposition bias voltage. In addition, the deviation in strength reduced significantly compared to bare SCS specimen.IEEE, 2017年, 30TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2017), 732 - 735, 英語
- A new tensile-mode parallel fatigue testing device with integrated shear strain gauge has been developed for reliability assessment of single crystal silicon (SCS) microstructures. We have previously reported a device with tensile strain gauge to test specimens a high stress and ultra-high cycles, however the test frequency was limited by the total stiffness of the testing system and the performance of piezoelectric actuator used for loading. In this report, we employed a shear strain gauge, which has higher stiffness than a tensile one. The testing device has five SCS specimens of 120 μm long, 4 μm wide and 5 μm thick, integrated with the shear strain gauge. We optimized the shear strain gauge by finite element analysis, and a gauge 15° tilted from orthogonal axis is the highest sensitivity in both dopant types. We performed parallel tensile testing with the device fabricated from n-type silicon-on-insulator wafer and confirmed output from the strain gauges. All five specimens fractured and the fracture strength of one of the specimens was measured as 1.15 GPa.一般社団法人 日本機械学会, 2016年, 年次大会, 2016, J2210105, 日本語
- This paper reports on the effect of diamond like carbon (DLC) coating on tensile fracture behavior of micro-scaled single crystal silicon (SCS) specimens. DLC film with the thickness of about 170 nm was fully coated on the surface of SCS specimens by plasma enhanced chemical vapor deposition (PECVD). DLC film was uniformly coated on SCS specimens of 5 μm thick and 4 μm wide. The average tensile strength of DLC coated specimens shows 13.4-53.5% higher values compared to that of the bare SCS specimens and Weibull modulus have a higher value, which indicates smaller deviations in strength. This result may lead to a further understanding for optimum design of DLC coated MEMS structure.一般社団法人 日本機械学会, 2016年, 年次大会, 2016, J2210305, 日本語
- Tensile testing of single crystal silicon microstructures was performed along tensile axes of <110> and <111> at 500 °C in a vacuum to investigate crystallographic effects on their slip occurrences and fracture behaviors at the high temperature. Specimens with parallel portions 120 μm long, 2 μm wide, and 5 μm thick, were designed along the two tensile axes on (110) wafers, and were fabricated from SOI (silicon-on-insulator) wafer using UV lithography and deep RIE (reactive ion etching) processes. The specimens were subjected to tensile testing at 500 °C in a vacuum, which exhibited linear stress increments until their fractures at 3.2 GPa on <110> and at 4.0 GPa on <111>. Contrary to the obtained linear nominal stress increments, fractured specimens possessed surface steps due to slip along {111}. The fracture surfaces exhibited large planes oriented mostly along {111} indicating cleavage fracture behaviors. Stress concentration around the surface step was analyzed employing finite element method to discuss effect on the surface step on decrease in nominal tensile strength at a high temperature, and criteria for slip were discussed based on maximum shear stress along the slip system.一般社団法人 日本機械学会, 2016年, 年次大会, 2016, J2210306, 日本語
- Copyright © 2016 The Authors. Published by Elsevier B.V. Effects of tensile orientations on fracture and slip behaviors of (110) single crystal silicon (SCS) microstructures at a high temperature are reported. Specimens with a parallel portion 120 μm long, 2 μm wide and 5μm thick were aligned along <110> and <111> tensile axes, and were fabricated from identical silicon-on-insulator wafers using UV lithography and a deep reactive ion etching. The specimens were subjected to tensile testing at 500 °C in a vacuum, which showed linear stress-displacement behaviors until their fractures at 3.2 GPa on <110> and at 4.0 GPa on <111>. The fracture surfaces mostly consisted of large planes oriented along {111}, which indicated cleavage fractures. Contrary to the obtained linear nominal stress behaviors, fractured specimens had surface steps owing to slip along {111}, which indicated that criteria for brittle-ductile transition of SCS were surpassed under the applied stress. Criteria for the slip occurrences were discussed based on maximum shear stress along the slip system, and stress concentration around the surface step was analyzed using finite element method calculation to discuss an effect of the surface step on decrease of nominal tensile strength at the high temperature.2016年01月01日, Procedia Structural Integrity, 2, 1413 - 1420
- 29pm3-PN-49 (110)単結晶シリコンマイクロ構造の高温引張破壊特性We report high-temperature tensile testing of (110) microstructures of single crystal silicon (SCS) to investigate a size effect on BDTT (brittle-ductile transition temperature). Specimens 5 μm wide and 5 μm thick were fabricated on (110) SOI (silicon-on-insulator) wafers with <100>, <110>, and <111> tensile axes. Since dislocations of SCS appear along (111) planes, measurement with different tensile axes would allow to clarify criteria of appearance of plastic deformations. <110>- and <111>-tensile specimens measured at 600 ℃ showed necking along (110) planes, and slip on (111) planes was also observed on surface of <111>-tensile specimens. It was interpreted that the necking was macroscopically along (110) but that was formed with aggregation of multiple slips along (111) planes.一般社団法人日本機械学会, 2015年10月21日, マイクロ・ナノ工学シンポジウム, 2015(7) (7), "29pm3 - PN-49-1"-"29pm3-PN-49-2", 日本語
- J2210404 ひずみゲージ集積型単結晶シリコンマイクロ構造の並列引張疲労試験We have proposed a method for tensile-mode fatigue testing of micro structures of single crystal silicon (SCS). For reliable measurements of fatigue property of SCS, a large number of cyclic loadings (10^6〜) and a sufficient number of measurements are necessary for statistical analysis, which requires very long measurements using tensile-mode fatigue testing, because the loading frequencies in reported tensile-mode fatigue testing are usually lower than 100 Hz. To shorten measurements, the proposed method conducts parallel measurements of testing structures. Arrayed testing structures with integrated piezoresistive strain gauges are subjected to tensile-mode fatigue testing simultaneously actuated using a piezoelectric stage. Because of the strain gauges with a linear and low noise output and a simple readout circuit, simultaneous measurement is realized. Designs of the testing structures and the strain gauges were reported, which allows us to use the piezoelectric stage and realizes quick measurements with higher test frequency.一般社団法人日本機械学会, 2015年09月13日, 年次大会 : Mechanical Engineering Congress, Japan, 2015, "J2210404 - 1"-"J2210404-3", 日本語
- 2014年10月, 第6回「マイクロ・ナノ工学シンポジウム」, 20pm3-PM005, 日本語単結晶シリコンマイクロ構造体の引張応力下における脆性延性遷移
- 2014年10月, The 27th International Microprocesses and Nanotechnology Conference, Fukuoka, Japan (4-7 October, 2014), 6C-5-1, 英語Tensile Testing in Vacuum with Concentrated Infrared Light Heating for Single Crystal Silicon Mechanical Characterization at High Temperature
- J2240303 赤外光集光加熱を用いた単結晶シリコンマイクロ構造体の真空中高温引張試験([J224-03]『マイクロ・ナノ機械の信頼性』のための材料創製・測定・解析技術 シリコンの破壊と疲労)High-temperature tensile testing for single crystal silicon microstructure up to 600 ℃ was conducted to reveal the size effect on the fracture properties, especially for the brittle-ductile transition temperature (BDTT). A newly developed tensile testing machine with concentrated infrared light heating was used for testing in a vacuum at high temperature. Beam specimens of 120 μm long, 4 μm wide and 5 μm thick which were designed for <110> tensile testing showed BDTT between 400 and 500 ℃, which is lower than bulk silicon of 600 ℃. The fracture strength also decreased by more than 50 % between the same temperature range, and slips on (111) crystal planes were observed on the fractured specimens. These results indicate that the dislocation slips caused stress concentration to decrease the tensile strength.一般社団法人日本機械学会, 2014年09月07日, 年次大会 : Mechanical Engineering Congress, Japan, 2014, "J2240303 - 1"-"J2240303-3", 日本語
- 2014年09月, 日本機械学会2014年度年次大会, J2240303, 日本語赤外集光加熱を用いた単結晶シリコンマイクロ構造体の真空中高温引張試験
- This paper reports the size effect of brittle-ductile transition temperature (BDTT) of micrometer sized single crystal silicon (120-μm long, 5-μm thick and 9-μm wide) using tensile testing in vacuum from RT to 600 ℃. The tensile testing results showed slope decrease of tensile stress-stage displacement curves and slips on (111) crystal planes at 500 ℃ and above, which indicated that the BDTT of micrometer sized silicon dropped compared to bulk structures. The fracture shapes also changed depending on temperature; specimens fractured from RT to 400 ℃ showed brittle fracture with fracture surfaces mainly on two (111) crystal planes starting at their sidewall damage, while specimens fractured at 600 ℃ had necking deformation. By comparing the results and previous research on the different sized specimens, we found that the dimension of slip-propagation direction, i.e. thickness, might dominate to the change in the BDTT.一般社団法人 日本機械学会, 2014年06月, The 7th Asia-Pacific Conference on Transducers and Micro/Nano Technologies (APCOT 2014), 2014.6, 0 - _20pm3-PM0, 英語
- 2014年01月, 日本実験力学会講演論文集, (14) (14), 265 - 267, 日本語単結晶シリコンの高温機械的特性評価に向けた赤外光集光加熱による真空中高温引張試験 (2014年度年次講演会)
- 2013年09月, 日本機械学会2013年度年次大会, 日本機械学会, J211013, 日本語(100)及び(110)単結晶シリコンにおける引張強度の結晶方位依存性
- 2013年07月, ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems (InterPACK 2013), 0, 英語Fractography Analysis Of Tensile Tested (110) Silicon Prepared by Different Surface Morphology And Crystal Orientations
- 2013年, 2013 Transducers and Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS and EUROSENSORS 2013, 1946 - 1949, 英語[査読有り]
- 2012年09月, 日本機械学会M&M2012材料力学カンファレンス, 2012, OS1909, 日本語加工条件の異なる(110)<111>単結晶シリコン薄膜の引張試験
- 2012年03月, The 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, 999 - 1000, 英語Modeling and elastic property simulation of epoxy-based negative photoresist using coarse-grained molecular dynamics
- A unique simulation method of epoxy-based chemically-amplified resist by coarse-grained molecular dynamics was proposed. The mechanical properties of an epoxy-based chemically-amplified resists with various cross-linking ratios were simulated using a newly developed coarse-grained molecular dynamics simulation that employs a bead-spring model. Models with the different cross-linking ratios were created in the molecular dynamics calculation step and uniaxial elongation simulations were performed. The results reveal that the simulated elastic modulus of the resist modeled by the bead-spring model with an extended angle bending potential depends on the cross-linking ratio; its dependency exhibits good agreement with that determined by nanoindentation tests. © 2012 Materials Research Society.2012年, Materials Research Society Symposium Proceedings, 1415, 59 - 64, 英語[査読有り]
- 2011年12月, Proceedings of International Workshop on Micro/Nano-Engineering, 88Coarse-Grained Molecular Dynamics Simulation Approach for Mechanical Property of Epoxy-Based Chemically-Amplified Resist
- 2011年09月, 第28回「センサ・マイクロマシンと応用システム」シンポジウム, 334 - 339, 日本語MEMS厚膜ネガレジストの粗視化分子動力学モデル
- 2011年09月, 日本機械学会2011年度年次大会, 2011, J161021, 日本語エポキシ系ネガレジスト機械的特性の架橋度依存性
- 2011年07月, The 16th International Conference on Solid-State Sensors Actuators and Microsystems (Transducers'11), 2706 - 2709, 英語[査読有り]
- 2011年06月, The 9th International Workshop on High-Aspect-Ratio Micro-Structure Technology (HARMST2011), 62 - 63, 英語Mechanical characterization of negative photoresist by nano-indentation for nano-filtration membrane[査読有り]
- 31st International Microprocesses and Nanotechnology Conference (MNC2018), 2018年11月, 英語, 国際会議Surface-Enhanced Raman Spectroscopy of DNA Bases Using Gold Nanoparticle Dimer Arrayポスター発表
- 31st International Microprocesses and Nanotechnology Conference (MNC2018), 2018年11月, 英語, 国際会議Development of 3D Formed Tactile Sensor by High Temperature Punch Creep Forming Technique口頭発表(一般)
- 第35回「センサ・マイクロマシンと応用システム」シンポジウム, 2018年10月, 日本語, 国内会議VLS成長SiNW単体に対する熱電変換特性評価ポスター発表
- 第35回「センサ・マイクロマシンと応用システム」シンポジウム, 2018年10月, 日本語, 国内会議Si薄膜被覆金ナノグレーティング構造の近赤外域光吸収スペクトル偏光依存性ポスター発表
- The 30th International Microprocesses and Nanotechnology Conference (MNC 2017), 2017年11月, 英語, Jeju, Korea, 国際会議Effect of Ge concentration on poly SiGe mechanical properties口頭発表(一般)
- 2017 International Conference on Solid State Devices and Materials (SSDM 2017), 2017年09月, 英語, Sendai, 国際会議Fatigue testing of poly-SiGe film using microresonatorポスター発表
- 日本学術振興会, 科学研究費助成事業 若手研究, 若手研究, 神戸大学, 2020年04月01日 - 2023年03月31日Core-shell Siナノ細線の熱電特性に対する界面電子状態の関与の解明高熱電変換効率を持つコアシェル(Core/shell)シリコンナノ細線(SiNWs)と、これを熱電素子とする発電モジュールの実現に向けて、令和2年度は、シリコンナノ細線を熱電変換素子として集積するための結晶成長方位制御技術の開発と、低不純物濃度半導体ナノ細線の電気伝導性にシェル薄膜が及ぼす影響の評価、Core/shellシリコンナノ細線の熱電特性を評価するための計測装置の開発と評価デバイスの試作を実施した。 シリコンナノ細線を熱電発電素子とする場合、特定の領域と特定の方向へと架橋成長させて集積させることが望ましいと考えられるが、従来のVLS(Vapor-Liquid-Solid)結晶成長法のみでこれを実現するのは容易ではなく、上記の開発において、触媒金ナノ粒子のシリコン基板表面での熱拡散処理と、メタルアシスト化学エッチング法、VLS結晶成長法を組み合わせた手法を開発することで、同一の触媒ナノ粒子を用いて基板表面にナノホール群を形成してから続けて結晶成長させることにより、シリコンナノ細線の初期の結晶成長を特定の結晶方位へと促進することに成功した。この手法はp型とn型のどちらの導電型のシリコン基板においても可能であり、シリコンナノ細線をユニレグ型およびπ型の熱電素子として集積するのに有効な手法と考えられる。 Core/shellシリコンナノ細線の熱電特性の評価に向けて、真空雰囲気下で,近赤外線レーザーによる評価デバイスの局所的な加熱を可能とする計測装置を開発した。真空下での計測により周囲気体を介した熱伝達が抑制され、微小領域に集積されたシリコンナノ細線の正確な熱電特性の把握が可能となる。また、シリコンナノ細線の架橋成長による集積後に表層不純物ドーピング・Core/shell構造化を行った熱電特性評価デバイスの試作を行った。今後、微細加工および熱電特性計測結果をもとに改良を進める。
- 日本学術振興会, 科学研究費補助金/基盤研究(A), 基盤研究(A), 神戸大学, 2017年04月 - 2021年03月生体内分解性インプラントは経時に伴い体内で分解されるため、抜去手術を必要としないデバイスとして注目されている。本研究ではインプラントの分解に伴う力学的強度をリアルタイムでモニタリングできるシステムの構築を目標としている。今年度は、第一原理計算に基づく分解性金属材料の最適組成設計およびヘテロ構造の形成を通じた強靱化に関する研究を継続して実施した。また、マイクロ検力センサーをインプラントへ実装するための接合に関する研究を推進した。 分解性金属材料の最適組成設計については、マグネシウム系合金のみならず亜鉛系合金について、第一原理計算による計算予測を前年度に引き続き実施するとともに、一部の合金について細線の創製を行った。マグネシウム細線については、カルシウム添加による高強度化と亜鉛の共添加による加工硬化性の向上を確認し、計算予測による元素添加の効果を細線についても得られることを実証した。一方、生体内における分解速度が比較的遅い亜鉛については、仕事関数を算出することにより、材料表面でイオン化しやすい添加元素の予測を行い、実験により分解性を評価した。例として、複数の結晶面にマグネシウム原子を添加することにより仕事関数が低下することが予測された。濃度の異なる合金を複数試作し、電気化学試験を行った結果から、マグネシウムの添加により分解性が上昇することを確認した。以上の結果を基に、亜鉛合金の細線を創製し、動物実験による性能確認試験を行った。 センサー材料の実装については、検力センサーをインプラント表面に実装するための基礎研究を推進した。位置決め方法および接合方法について、多数の試行を行い、インプラント表面へ分解性検力センサーを実装する手法を確立した。競争的資金
- 日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 特別研究員奨励費, 京都大学, 2013年04月01日 - 2016年03月31日マイクロ機械構造体の信頼性向上のための単結晶シリコンの破壊特性評価1.マイクロからナノスケールまでの構造体の破壊特性の評価: 本研究では高温環境で単結晶シリコン微細構造に対して引張試験を行い,構造寸法・周囲温度が破壊強度に及ぼす影響だけではなく,脆性延性遷移温度に対する構造寸法の影響についても評価を行っている.前年度までに開発を行った赤外集光加熱を用いた高温真空引張試験装置を用い,面方位(110)の引張軸方位の異なる試験片の測定に取り組んだ.500 °Cにて高温引張試験を行ったところ,すべりの発生部と試験片の破断部の位置関係に引張軸方位に依存した差異が確認された.<110>方位の試験片ではすべりによって生じたステップの近傍で破壊が始まっており,これは高温下での破壊強度の低下に関係しているものと考えられる.今後,より多様な温度条件の下,引張軸方位だけではなく幅寸法も変更した試験片の高温引張試験を実施する予定である.
2.引張疲労試験: 単結晶シリコンの高サイクル引張疲労特性を短時間で多数計測する手法として,集積化ひずみゲージを用いた並列引張試験方法の開発に取り組んだ.この手法では,並列化による試験片一つ当たりの測定時間の短縮と,測定系の高剛性化による繰返し負荷周波数の向上が期待される.集積したひずみゲージの検証実験では,線形性の良い低ノイズのブリッジ出力電圧が計測され,提案手法の有効性が確認された.また,試験片を5個配列した並列試験の検証実験では各試験片の負荷開始点・破断点がブリッジ出力電圧の変化によって明瞭に示された.測定系の高剛性化によって測定に必要なアクチュエータの変位が低減されており,試作デバイスでは110Hzの引張疲労試験が実現可能である.今後,計測精度向上のための改良を行い,疲労試験を実施する予定である.
研究シーズ
■ 研究シーズ- 半導体ナノワイヤのマルチフィジックス特性評価とデバイス応用シーズカテゴリ:ナノテク・材料, エネルギー, ものづくり技術(機械・電気電子・化学工業)研究キーワード:MEMS, 微細加工, ナノワイヤ, 熱電発電研究の背景と目的:半導体材料をナノスケールまで微細化させると、電気的、機械的物性が大きく変化することがあります。そのようなナノスケールで現れる物性を有効に活用することで、従来の素子では到達しえなかった高機能化・高性能化の実現が期待されます。シリコン系半導体のナノワイヤに焦点をあてて、そのデバイス応用にむけて、電気的、機械的物性の評価を行うとともに、微小なデバイス上への集積手法についてもあわせて研究を進めています。研究内容:『シリコンナノワイヤ熱電素子応用に関する研究』 廃熱から電気エネルギーを回収する熱電変換発電が注目されています。従来のBi-Te系熱電材料は資源希少性などの問題があり、代替素子が求められています。半導体材料は熱電効果を有し、ナノ構造では熱伝導が抑えられて変換効率を向上することができます。本研究ではさらに、ナノワイヤの電気伝導性に着目したコアシェル構造化などを合せることで、変換効率の向上を目指しています。 『シリコンナノワイヤ集積技術に関する研究』 結晶成長シリコンナノワイヤを、MEMSなどのデバイスに応用し、その導電特性を有効活用するためには、所望の場所・方向へと成長させて集積することが重要です。UVリソグラフィによる触媒粒子配列技術と組合せた基板内で水平成長・接続させる手法の開発や、ナノスケールの表面加工処理を組合せることで特定方向への成長比率を増加させる手法の開発を行っています。期待される効果や応用分野:・シリコンナノワイヤ構造を用いた熱電発電素子開発。 ・シリコンナノワイヤ集積を用いた微小サイズの高感度力覚センサ応用。関係する業績:Akio Uesugi et al, "Vapor-liquid-solid growth of silicon nanowires from surface nanoholes formed with metal-assisted chemical etching", Jpn. J. Appl. Phys., vol. 60, no. 5, 055502 (2021)