Pub Date : 2024-07-15DOI: 10.35848/1347-4065/ad5f6c
Kouta Ozaki, Keita Kikuchi, Guangtao Zhu, Kohei Noda, Yuguo Yao, Yuangang Lu, Rajan Jha, Heeyoung Lee and Yosuke Mizuno
Brillouin optical correlation-domain reflectometry (BOCDR) allows for relatively high spatial resolution and random accessibility with single-end light injection into the sensing fiber. Typically, BOCDR relies on directly modulating the laser diode’s driving current, which facilitates sinusoidal frequency modulation for distributed sensing but also introduces unintended power modulation that can degrade performance. To address these power variations, external-modulation BOCDR using a double-sideband modulator has been developed. However, this method generates substantial noise, overpowering the Brillouin signal and impeding accurate strain and temperature measurements. This study clarifies the previously unexplained noise mechanisms and suggests system design optimizations to mitigate their impact.
{"title":"Noise mechanism clarification in external-modulation Brillouin optical correlation-domain reflectometry with double-sideband modulator","authors":"Kouta Ozaki, Keita Kikuchi, Guangtao Zhu, Kohei Noda, Yuguo Yao, Yuangang Lu, Rajan Jha, Heeyoung Lee and Yosuke Mizuno","doi":"10.35848/1347-4065/ad5f6c","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5f6c","url":null,"abstract":"Brillouin optical correlation-domain reflectometry (BOCDR) allows for relatively high spatial resolution and random accessibility with single-end light injection into the sensing fiber. Typically, BOCDR relies on directly modulating the laser diode’s driving current, which facilitates sinusoidal frequency modulation for distributed sensing but also introduces unintended power modulation that can degrade performance. To address these power variations, external-modulation BOCDR using a double-sideband modulator has been developed. However, this method generates substantial noise, overpowering the Brillouin signal and impeding accurate strain and temperature measurements. This study clarifies the previously unexplained noise mechanisms and suggests system design optimizations to mitigate their impact.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"20 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.35848/1347-4065/ad5ba0
Yoshiharu Kitayama, Mitsuhiro Nogami and Keitaro Hitomi
We constructed a gamma-ray imager that estimates the distribution of gamma-ray sources based on the response patterns of multiple gamma-ray detectors randomly positioned in three-dimensional space. The Coded Cube Camera for Gamma-ray (C3G), comprising eight Gd3Al2Ga3O12 (Ce) scintillator and eighteen lead cubes is housed in a cubical casing with an 86 mm edge length and weighs approximately 600 g. The results of the 4π imaging experiment confirmed the feasibility of imaging a 10 MBq 137Cs source 3 m away for a 10 min measurement. C3G operates with only eight channels, instead of the hundreds needed by a typical imager. This setup allows for a simplified circuit and reconstruction algorithm, resulting in a cost-effective and reliable system. With its compact and lightweight design and 4π field of view, this technology is expected to find extensive applications in astronomy, medicine, nuclear security, and decommissioning projects.
{"title":"An experimental feasibility study of a 4π gamma-ray imager using detector response patterns","authors":"Yoshiharu Kitayama, Mitsuhiro Nogami and Keitaro Hitomi","doi":"10.35848/1347-4065/ad5ba0","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5ba0","url":null,"abstract":"We constructed a gamma-ray imager that estimates the distribution of gamma-ray sources based on the response patterns of multiple gamma-ray detectors randomly positioned in three-dimensional space. The Coded Cube Camera for Gamma-ray (C3G), comprising eight Gd3Al2Ga3O12 (Ce) scintillator and eighteen lead cubes is housed in a cubical casing with an 86 mm edge length and weighs approximately 600 g. The results of the 4π imaging experiment confirmed the feasibility of imaging a 10 MBq 137Cs source 3 m away for a 10 min measurement. C3G operates with only eight channels, instead of the hundreds needed by a typical imager. This setup allows for a simplified circuit and reconstruction algorithm, resulting in a cost-effective and reliable system. With its compact and lightweight design and 4π field of view, this technology is expected to find extensive applications in astronomy, medicine, nuclear security, and decommissioning projects.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"15 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141719955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.35848/1347-4065/ad5cb3
Ryo Tabata, Ryosuke Matsubara and Atsushi Kubono
Increasing the surface coverage of antifouling materials is essential to enhance the performance of antifouling coatings. In this study, polyurea thin-film underlayers were fabricated by co-depositing difunctional isocyanates with difunctional or trifunctional amines. The relationships among the underlayer structure, terminal group density before polyethylene glycol (PEG) termination, and PEG surface coverage were investigated. The results showed that employing trifunctional amines in the underlayer led to increased terminal group density before PEG termination. Moreover, the reduced hydrogen-bonding capability between the polyurea molecules contributes to enhanced PEG surface coverage.
{"title":"Relationship between the polyurea underlayer structure and PEG surface coverage","authors":"Ryo Tabata, Ryosuke Matsubara and Atsushi Kubono","doi":"10.35848/1347-4065/ad5cb3","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5cb3","url":null,"abstract":"Increasing the surface coverage of antifouling materials is essential to enhance the performance of antifouling coatings. In this study, polyurea thin-film underlayers were fabricated by co-depositing difunctional isocyanates with difunctional or trifunctional amines. The relationships among the underlayer structure, terminal group density before polyethylene glycol (PEG) termination, and PEG surface coverage were investigated. The results showed that employing trifunctional amines in the underlayer led to increased terminal group density before PEG termination. Moreover, the reduced hydrogen-bonding capability between the polyurea molecules contributes to enhanced PEG surface coverage.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"7 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We adopt a buried nanomagnet (BNM) technology on a one-dimensional (1D) array of silicon spin qubits, and its availability was investigated using numerical simulations. The qubit array is formed in the center of the Si fin and the nanomagnet is buried in the lower lateral part of the qubits. The nanomagnet placed near the qubit generates a strong slanting magnetic field in the qubit, enabling X-gate operation approximately 15 times faster than in conventional cases. Furthermore, the formation of a BNM using a self-aligned process suppresses the dimensional variation of the nanomagnet caused by process variation, thereby mitigating the slanting field fluctuation and fidelity degradation. In addition, even for multiple qubits formed in the Si fin, the BNM with excess length generated a uniform slanting field, mitigating fidelity degradation and enabling all qubits to operate using a single-frequency microwave. Therefore, the proposed structure is useful for 1D integrated structures.
我们在一维（1D）硅自旋量子比特阵列上采用了埋入式纳米磁体（BNM）技术，并通过数值模拟研究了该技术的可用性。量子位阵列形成于硅翅片的中心，纳米磁体埋设在量子位的下侧部分。放置在量子位附近的纳米磁体会在量子位中产生强大的斜磁场，从而使 X 门的运行速度比传统情况下快约 15 倍。此外，利用自对准工艺形成的 BNM 可抑制纳米磁体因工艺变化而产生的尺寸变化，从而减轻斜磁场波动和保真度下降。此外，即使在硅翅片中形成多个量子比特，超长的 BNM 也能产生均匀的斜场，从而减轻保真度下降，并使所有量子比特都能使用单频微波工作。因此，所提出的结构适用于一维集成结构。
{"title":"Integration of buried nanomagnet and silicon spin qubits in a one-dimensional fin structure","authors":"Shota Iizuka, Kimihiko Kato, Atsushi Yagishita, Hidehiro Asai, Tetsuya Ueda, Hiroshi Oka, Junichi Hattori, Tsutomu Ikegami, Koichi Fukuda, Takahiro Mori","doi":"10.35848/1347-4065/ad59ea","DOIUrl":"https://doi.org/10.35848/1347-4065/ad59ea","url":null,"abstract":"We adopt a buried nanomagnet (BNM) technology on a one-dimensional (1D) array of silicon spin qubits, and its availability was investigated using numerical simulations. The qubit array is formed in the center of the Si fin and the nanomagnet is buried in the lower lateral part of the qubits. The nanomagnet placed near the qubit generates a strong slanting magnetic field in the qubit, enabling X-gate operation approximately 15 times faster than in conventional cases. Furthermore, the formation of a BNM using a self-aligned process suppresses the dimensional variation of the nanomagnet caused by process variation, thereby mitigating the slanting field fluctuation and fidelity degradation. In addition, even for multiple qubits formed in the Si fin, the BNM with excess length generated a uniform slanting field, mitigating fidelity degradation and enabling all qubits to operate using a single-frequency microwave. Therefore, the proposed structure is useful for 1D integrated structures.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"13 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141571352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.35848/1347-4065/ad5aca
Shunsuke Shitakata, Hiroshi Oka, Takumi Inaba, Shota Iizuka, Hidehiro Asai, Kimihiko Kato and Takahiro Mori
This study experimentally investigated the effects of an additional high-pressure hydrogen annealing (HPHA) on the cryogenic operation of Si (110)-oriented n-MOSFETs. The HPHA induced improvements in the subthreshold swing (SS), threshold voltage (Vth), and ON current at cryogenic temperatures. Further, we analyzed the SS-drain current curves using the analytical model and concluded that HPHA reduced the density of the band-edge states. In addition, the analysis of the temperature-dependent Vth supported this conclusion. Furthermore, effective mobility analysis results indicated that the improvement in the ON current was attributable to the improvement in the band-edge states. Therefore, we conclude that the HPHA process positively affected the Si/SiO2 interface and reduced the interface-related band-edge states, thereby improving the cryogenic operation of MOSFETs.
{"title":"High-pressure hydrogen annealing improving the cryogenic operation of Si (110)-oriented n-MOSFETs","authors":"Shunsuke Shitakata, Hiroshi Oka, Takumi Inaba, Shota Iizuka, Hidehiro Asai, Kimihiko Kato and Takahiro Mori","doi":"10.35848/1347-4065/ad5aca","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5aca","url":null,"abstract":"This study experimentally investigated the effects of an additional high-pressure hydrogen annealing (HPHA) on the cryogenic operation of Si (110)-oriented n-MOSFETs. The HPHA induced improvements in the subthreshold swing (SS), threshold voltage (Vth), and ON current at cryogenic temperatures. Further, we analyzed the SS-drain current curves using the analytical model and concluded that HPHA reduced the density of the band-edge states. In addition, the analysis of the temperature-dependent Vth supported this conclusion. Furthermore, effective mobility analysis results indicated that the improvement in the ON current was attributable to the improvement in the band-edge states. Therefore, we conclude that the HPHA process positively affected the Si/SiO2 interface and reduced the interface-related band-edge states, thereby improving the cryogenic operation of MOSFETs.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"46 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-08DOI: 10.35848/1347-4065/ad5978
Hengheng Zhang, Min Lai, Yuxin Chen, Yutong Qi, Bao Zhu, Xuefei Xiao, Xingchen Zhou, Yan Ma
The fabrication of an evanescent wave fiber optic humidity sensor based on bromophenol blue (BPB) doped SiO2 thin film was demonstrated, modulating in light intensity. The sensing film was coated on a fiber core via a single-step dip coating method, followed by sol-gel processing of the precursor. A good exponential relationship was established between output light intensity and relative humidity. The sensor exhibited a high sensitivity and fast response and recovery, as well as low hysteresis, good stability and repeatability. Adsorption of ambient water triggered a ring-opening reaction of BPB, which enhanced light absorption of the sensing film significantly and affected the transmission of the evanescent wave.
{"title":"Humidity sensing by tailoring light absorption of SiO2/bromophenol blue (BPB) thin film on optical fiber","authors":"Hengheng Zhang, Min Lai, Yuxin Chen, Yutong Qi, Bao Zhu, Xuefei Xiao, Xingchen Zhou, Yan Ma","doi":"10.35848/1347-4065/ad5978","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5978","url":null,"abstract":"The fabrication of an evanescent wave fiber optic humidity sensor based on bromophenol blue (BPB) doped SiO<sub>2</sub> thin film was demonstrated, modulating in light intensity. The sensing film was coated on a fiber core via a single-step dip coating method, followed by sol-gel processing of the precursor. A good exponential relationship was established between output light intensity and relative humidity. The sensor exhibited a high sensitivity and fast response and recovery, as well as low hysteresis, good stability and repeatability. Adsorption of ambient water triggered a ring-opening reaction of BPB, which enhanced light absorption of the sensing film significantly and affected the transmission of the evanescent wave.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"21 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141571353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.35848/1347-4065/ad5299
Sara Bruhier, Haisong Jiang and Kiichi Hamamoto
In response to the global aging population, a photonic-integrated-circuit sensor is investigated for the detection of disease markers within human breath content. The device relies on cavity-ring-down spectroscopy with an amplifying medium and loop feedback to secure sufficient sensitivity down to ppm-order concentration detection. This configuration, however, might cause unwanted oscillation, and the polarization rotation method has been proposed to prevent this issue. We have researched a waveguide-based polarization rotator using nano-pixels. The device consists of two regions: (1) From TE00 mode TE10 modes conversion and (2) TE10 to TM00 modes conversion. As the intermediary TE10 mode quality is key to realizing polarization rotation performance, the purpose of this study is to realize high-quality TE10 by employing the mean-squared-error criterion for waveguide design optimization. A finite-difference time-domain simulation with this method reveals a TE10 mode with 1% accuracy that results in a polarization extinction ratio improved from 4.3 to 8.6 dB.
{"title":"Nano-pixel polarization rotator for a photonic integrated breath sensor","authors":"Sara Bruhier, Haisong Jiang and Kiichi Hamamoto","doi":"10.35848/1347-4065/ad5299","DOIUrl":"https://doi.org/10.35848/1347-4065/ad5299","url":null,"abstract":"In response to the global aging population, a photonic-integrated-circuit sensor is investigated for the detection of disease markers within human breath content. The device relies on cavity-ring-down spectroscopy with an amplifying medium and loop feedback to secure sufficient sensitivity down to ppm-order concentration detection. This configuration, however, might cause unwanted oscillation, and the polarization rotation method has been proposed to prevent this issue. We have researched a waveguide-based polarization rotator using nano-pixels. The device consists of two regions: (1) From TE00 mode TE10 modes conversion and (2) TE10 to TM00 modes conversion. As the intermediary TE10 mode quality is key to realizing polarization rotation performance, the purpose of this study is to realize high-quality TE10 by employing the mean-squared-error criterion for waveguide design optimization. A finite-difference time-domain simulation with this method reveals a TE10 mode with 1% accuracy that results in a polarization extinction ratio improved from 4.3 to 8.6 dB.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"33 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-30DOI: 10.35848/1347-4065/ad52da
Igor Prozheev, Tanja Heikkinen, Ilja Makkonen, Kenichiro Mizohata and Filip Tuomisto
We report positron annihilation results on in-grown and proton-irradiation-induced vacancy defects in AlN single crystals grown by physical vapor transport. The samples were irradiated with 100 keV H+ ions to varying fluences in the range of 5 × 1014 − 2 × 1018 ions cm–2. Doppler broadening of annihilation radiation was recorded in as-grown and irradiated samples with a slow positron beam with varying implantation energy. Doppler results combined with first principles theoretical calculations show that the 100 keV H+ irradiation introduces isolated VAl on the ion track and VN-rich vacancy clusters at the end of the ion range. The results suggest that the excess amount of detected VN originates from a high concentration of in-grown VN. So far, these defects have been considered to be unidentified negative ion-like defects in AlN.
{"title":"In-grown and irradiation-induced Al and N vacancies in 100 keV H+ implanted AlN single crystals","authors":"Igor Prozheev, Tanja Heikkinen, Ilja Makkonen, Kenichiro Mizohata and Filip Tuomisto","doi":"10.35848/1347-4065/ad52da","DOIUrl":"https://doi.org/10.35848/1347-4065/ad52da","url":null,"abstract":"We report positron annihilation results on in-grown and proton-irradiation-induced vacancy defects in AlN single crystals grown by physical vapor transport. The samples were irradiated with 100 keV H+ ions to varying fluences in the range of 5 × 1014 − 2 × 1018 ions cm–2. Doppler broadening of annihilation radiation was recorded in as-grown and irradiated samples with a slow positron beam with varying implantation energy. Doppler results combined with first principles theoretical calculations show that the 100 keV H+ irradiation introduces isolated VAl on the ion track and VN-rich vacancy clusters at the end of the ion range. The results suggest that the excess amount of detected VN originates from a high concentration of in-grown VN. So far, these defects have been considered to be unidentified negative ion-like defects in AlN.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"31 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-25DOI: 10.35848/1347-4065/ad52d9
Anthony Tuico, John Paul Ferrolino, Neil Irvin Cabello, Ivan Cedrick Verona, Wilson Garcia, Arnel Salvador, Hannah Bardolaza, Elmer Estacio and Alexander De Los Reyes
We report on the terahertz (THz) emission polarization characteristics of spintronic nickel/platinum (Ni/Pt) bilayer films. The films were deposited on MgO substrates via electron beam deposition with varying Ni thicknesses of 5, 7, and 9 nm and a constant Pt thickness of 6 nm. Results from B-field polarity-dependent THz measurements exhibited different THz emission characteristics for the p- and s-polarized components. We attribute the strong, wide-bandwidth B-field dependent p-polarized component to the inverse spin Hall effect and the weak, low-bandwidth B-field independent s-polarized component to the ultrafast demagnetization process. The peak-to-peak THz emission amplitudes were demonstrated to be dependent on the sample rotational angle about the optical axis which suggests sample inhomogeneity from the deposited Ni/Pt spintronic films. These results are crucial for the material design and development of more intense spintronic THz sources.
我们报告了自旋电子镍/铂（Ni/Pt）双层薄膜的太赫兹（THz）发射极化特性。这些薄膜是通过电子束沉积法沉积在氧化镁基底上的，镍的厚度分别为 5、7 和 9 纳米，铂的厚度恒定为 6 纳米。根据 B 场极性进行的太赫兹测量结果显示，p 极和 s 极分量具有不同的太赫兹发射特性。我们将与 B 场相关的强宽带对极化分量归因于反自旋霍尔效应，而与 B 场无关的弱低带宽 s 极化分量则归因于超快退磁过程。峰-峰太赫兹发射振幅与样品围绕光轴的旋转角度有关，这表明沉积的镍/铂自旋电子薄膜存在样品不均匀性。这些结果对于更高强度的自旋电子太赫兹源的材料设计和开发至关重要。
{"title":"Polarization characteristics of Ni/Pt-based spintronic terahertz emitters based on spin electron dynamics","authors":"Anthony Tuico, John Paul Ferrolino, Neil Irvin Cabello, Ivan Cedrick Verona, Wilson Garcia, Arnel Salvador, Hannah Bardolaza, Elmer Estacio and Alexander De Los Reyes","doi":"10.35848/1347-4065/ad52d9","DOIUrl":"https://doi.org/10.35848/1347-4065/ad52d9","url":null,"abstract":"We report on the terahertz (THz) emission polarization characteristics of spintronic nickel/platinum (Ni/Pt) bilayer films. The films were deposited on MgO substrates via electron beam deposition with varying Ni thicknesses of 5, 7, and 9 nm and a constant Pt thickness of 6 nm. Results from B-field polarity-dependent THz measurements exhibited different THz emission characteristics for the p- and s-polarized components. We attribute the strong, wide-bandwidth B-field dependent p-polarized component to the inverse spin Hall effect and the weak, low-bandwidth B-field independent s-polarized component to the ultrafast demagnetization process. The peak-to-peak THz emission amplitudes were demonstrated to be dependent on the sample rotational angle about the optical axis which suggests sample inhomogeneity from the deposited Ni/Pt spintronic films. These results are crucial for the material design and development of more intense spintronic THz sources.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"40 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-24DOI: 10.35848/1347-4065/ad53b1
Taro Kato, Takahisa Tanaka and Ken Uchida
We demonstrated Joule-heated Au nanosheet H2S sensors for low-power operation. We confirmed that low temperature regions in the Joule-heated Au nanosheet caused lower response and recovery characteristics than uniformly heated Au nanosheets. By using Pt electrodes, which has lower thermal conductivity than Au, heat dissipation to the electrodes could be suppressed, resulting in lower power consumption and faster recovery characteristics. We then discussed the optimal sensor structure by developing an analytical model of electrical and thermal resistances. We introduced semi-elliptical intermediate electrodes between the channel and pad electrodes to efficiently suppress the heat dissipation, demonstrating that the optimal channel length and thermal conductivity of the intermediate electrode κint exist depending on the channel width. Finally, we proposed the sensor design strategy of considering the κint dependences of the electrical and thermal resistances. This strategy is useful for all metal nanosheet sensors because it gives an estimation of their optimal structures.
{"title":"Thermal-aware device design of low-power H2S sensors using Joule-heated Au nanosheet","authors":"Taro Kato, Takahisa Tanaka and Ken Uchida","doi":"10.35848/1347-4065/ad53b1","DOIUrl":"https://doi.org/10.35848/1347-4065/ad53b1","url":null,"abstract":"We demonstrated Joule-heated Au nanosheet H2S sensors for low-power operation. We confirmed that low temperature regions in the Joule-heated Au nanosheet caused lower response and recovery characteristics than uniformly heated Au nanosheets. By using Pt electrodes, which has lower thermal conductivity than Au, heat dissipation to the electrodes could be suppressed, resulting in lower power consumption and faster recovery characteristics. We then discussed the optimal sensor structure by developing an analytical model of electrical and thermal resistances. We introduced semi-elliptical intermediate electrodes between the channel and pad electrodes to efficiently suppress the heat dissipation, demonstrating that the optimal channel length and thermal conductivity of the intermediate electrode κint exist depending on the channel width. Finally, we proposed the sensor design strategy of considering the κint dependences of the electrical and thermal resistances. This strategy is useful for all metal nanosheet sensors because it gives an estimation of their optimal structures.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"12 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141517910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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