Pub Date : 2024-09-10DOI: 10.35848/1347-4065/ad6ed5
Qiuen Li, Xuanwu Kang, Hao Wu, Rikang Zhao, Yingkui Zheng, Hengyu Shang, Xinyu Liu and Chengjun Huang
In this study, a thin barrier AlGaN/GaN heterojunction diode with a NiO anode is proposed. NiO as an anode combined with a 5 nm AlGaN barrier layer can significantly deplete two-dimensional electron gas in the anode region of the device. Combined with the etching-free technology, the damage caused by etching the AlGaN barrier layer is successfully avoided. The capacitance of the device was reduced from 28 pF mm−1 (Schottky) to 966 fF/mm (NiO) which reduced 97%. At the same time the NiO anode devices with a reverse current leakage of ~10−8 A/mm@−100V achieved a high current ON/OFF ratio of ~10-8. NiO not only reduces the capacitance and leakage of the device but also enhances its anti-collapse ability. Without using the structure of field plates, the breakdown voltage of the device was also increased compared with the Schottky diode.
{"title":"Capacitance reduction in AlGaN/GaN heterojunction diodes through thermally oxidized NiO anode","authors":"Qiuen Li, Xuanwu Kang, Hao Wu, Rikang Zhao, Yingkui Zheng, Hengyu Shang, Xinyu Liu and Chengjun Huang","doi":"10.35848/1347-4065/ad6ed5","DOIUrl":"https://doi.org/10.35848/1347-4065/ad6ed5","url":null,"abstract":"In this study, a thin barrier AlGaN/GaN heterojunction diode with a NiO anode is proposed. NiO as an anode combined with a 5 nm AlGaN barrier layer can significantly deplete two-dimensional electron gas in the anode region of the device. Combined with the etching-free technology, the damage caused by etching the AlGaN barrier layer is successfully avoided. The capacitance of the device was reduced from 28 pF mm−1 (Schottky) to 966 fF/mm (NiO) which reduced 97%. At the same time the NiO anode devices with a reverse current leakage of ~10−8 A/mm@−100V achieved a high current ON/OFF ratio of ~10-8. NiO not only reduces the capacitance and leakage of the device but also enhances its anti-collapse ability. Without using the structure of field plates, the breakdown voltage of the device was also increased compared with the Schottky diode.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"7 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227051","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 : 2024-09-10DOI: 10.35848/1347-4065/ad6f87
Masahiro Kaneko, Hiroki Miyake and Hiroyuki Nishinaka
This study demonstrates the successful growth of a β-(AlxGa1−x)2O3/β-Ga2O3 superlattice structure with six periods using mist CVD. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis revealed that the superlattice consisted of six periods of β-(AlxGa1−x)2O3/β-Ga2O3 with an individual layer thickness of 12.9 nm and 9.1 nm, respectively. XRD analysis further confirmed the periodicity of the structure, yielding a period of 22.7 nm, which is in good agreement with the STEM result. Additionally, the Al composition was determined to be x = 0.085 based on XRD peak positions. Both atomic force microscopy and HAADF-STEM observations revealed atomically flat surfaces and sharp interfaces. This achievement highlights the potential of mist CVD for fabricating complex oxide heterostructures, offering a cost-effective and scalable alternative to conventional methods. The findings open new avenues for developing advanced electronic and optoelectronic devices based on wide-bandgap oxides.
{"title":"Demonstration of β-(Al x Ga1−x )2O3/β-Ga2O3 superlattice growth by mist chemical vapor deposition","authors":"Masahiro Kaneko, Hiroki Miyake and Hiroyuki Nishinaka","doi":"10.35848/1347-4065/ad6f87","DOIUrl":"https://doi.org/10.35848/1347-4065/ad6f87","url":null,"abstract":"This study demonstrates the successful growth of a β-(AlxGa1−x)2O3/β-Ga2O3 superlattice structure with six periods using mist CVD. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis revealed that the superlattice consisted of six periods of β-(AlxGa1−x)2O3/β-Ga2O3 with an individual layer thickness of 12.9 nm and 9.1 nm, respectively. XRD analysis further confirmed the periodicity of the structure, yielding a period of 22.7 nm, which is in good agreement with the STEM result. Additionally, the Al composition was determined to be x = 0.085 based on XRD peak positions. Both atomic force microscopy and HAADF-STEM observations revealed atomically flat surfaces and sharp interfaces. This achievement highlights the potential of mist CVD for fabricating complex oxide heterostructures, offering a cost-effective and scalable alternative to conventional methods. The findings open new avenues for developing advanced electronic and optoelectronic devices based on wide-bandgap oxides.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"7 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218096","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 : 2024-09-10DOI: 10.35848/1347-4065/ad7433
Daiki Kanamori and Mutsumi Sugiyama
This study explores the potential of Ge-enhanced Cu2SnS3 (CTS) thin-films as photoelectrode materials for water splitting grown through a simple sulfurization process. The addition of Ge to CTS enabled tuning the bandgap and improved the photocurrent density. Films sulfurized at 520 °C exhibit enhanced grain size and reduced grain boundaries, which contribute to increased carrier transport efficiency. By optimizing Ge content and sulfurization conditions, the Cu2(Sn1−x,Gex)S3 films demonstrate promising capabilities for efficient green hydrogen production. This work lays the groundwork for developing advanced photoelectrodes and highlights the need for further refinement to maximize performance for practical applications.
本研究探讨了通过简单的硫化工艺生长的 Ge 增强 Cu2SnS3(CTS)薄膜作为光电极材料用于水分离的潜力。在 CTS 中添加 Ge 能够调整带隙并提高光电流密度。在 520 °C 下硫化的薄膜显示出更大的晶粒尺寸和更小的晶界,这有助于提高载流子传输效率。通过优化 Ge 含量和硫化条件,Cu2(Sn1-x,Gex)S3 薄膜展现出了高效绿色制氢的潜力。这项工作为开发先进的光电电极奠定了基础,并强调了进一步改进的必要性,以最大限度地提高实际应用的性能。
{"title":"A preliminary investigation into the potential of Ge-enhanced Cu2SnS3 (CTS) thin-film applications for water-splitting photoelectrodes","authors":"Daiki Kanamori and Mutsumi Sugiyama","doi":"10.35848/1347-4065/ad7433","DOIUrl":"https://doi.org/10.35848/1347-4065/ad7433","url":null,"abstract":"This study explores the potential of Ge-enhanced Cu2SnS3 (CTS) thin-films as photoelectrode materials for water splitting grown through a simple sulfurization process. The addition of Ge to CTS enabled tuning the bandgap and improved the photocurrent density. Films sulfurized at 520 °C exhibit enhanced grain size and reduced grain boundaries, which contribute to increased carrier transport efficiency. By optimizing Ge content and sulfurization conditions, the Cu2(Sn1−x,Gex)S3 films demonstrate promising capabilities for efficient green hydrogen production. This work lays the groundwork for developing advanced photoelectrodes and highlights the need for further refinement to maximize performance for practical applications.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"13 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218105","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 : 2024-09-08DOI: 10.35848/1347-4065/ad70bf
Hideaki Tanimura, Yuma Ueno, Tomoya Mifune, Hironori Fujisawa, Seiji Nakashima, Ai I. Osaka, Shinichi Kato and Takumi Mikawa
We report the use of a low-thermal-budget annealing technique; flash lamp annealing (FLA), which provides an extremely short annealing time in the millisecond range, on the ferroelectric properties of Al-doped HfO2 (HAO) films. HAO annealed at 1000 °C with 5 ms shows a higher remanent polarization value of 24.9 μC cm−2 compared to rapid thermal annealing (RTA), without degradation of endurance. GIXRD shows a stronger peak intensity originating from the orthorhombic (o-) phase and is observed when using FLA, indicating the formation of a larger amount of the o-phase. We believe that this is a consequence of the low thermal budget of FLA, and that specifically FLA can minimize the relaxation of the compressive stress in the TiN electrodes, inducing a high tensile stress to the HAO films and therefore an enhancement of o-phase formation. These results indicate that FLA is a promising annealing method for HAO crystallization due to the enhancement of o-phase formation.
{"title":"Low-thermal-budget crystallization of ferroelectric Al:HfO2 films by millisecond flash lamp annealing","authors":"Hideaki Tanimura, Yuma Ueno, Tomoya Mifune, Hironori Fujisawa, Seiji Nakashima, Ai I. Osaka, Shinichi Kato and Takumi Mikawa","doi":"10.35848/1347-4065/ad70bf","DOIUrl":"https://doi.org/10.35848/1347-4065/ad70bf","url":null,"abstract":"We report the use of a low-thermal-budget annealing technique; flash lamp annealing (FLA), which provides an extremely short annealing time in the millisecond range, on the ferroelectric properties of Al-doped HfO2 (HAO) films. HAO annealed at 1000 °C with 5 ms shows a higher remanent polarization value of 24.9 μC cm−2 compared to rapid thermal annealing (RTA), without degradation of endurance. GIXRD shows a stronger peak intensity originating from the orthorhombic (o-) phase and is observed when using FLA, indicating the formation of a larger amount of the o-phase. We believe that this is a consequence of the low thermal budget of FLA, and that specifically FLA can minimize the relaxation of the compressive stress in the TiN electrodes, inducing a high tensile stress to the HAO films and therefore an enhancement of o-phase formation. These results indicate that FLA is a promising annealing method for HAO crystallization due to the enhancement of o-phase formation.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"65 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218099","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 : 2024-09-08DOI: 10.35848/1347-4065/ad71d8
Ryota Yoshida, Shoki Nezu and Koji Sekiguchi
We investigated the dynamics of spin waves in micro-patterned Permalloy thin films using time-resolved magneto-optic Kerr effect microscopy (TR-MOKE). By applying an external magnetic field, we observe the field dependence of spin wave signals with picosecond resolution. Fourier transform analysis of the signals confirms their agreement with the dispersion relation, demonstrating the successful detection of propagating spin waves using the MOKE technique. Furthermore, we perform dynamic measurements of interfering spin waves generated by a V-shaped antenna. The experimental results reveal differences in spin wave amplitude at each detection point. In combination with simulation analysis based on wave propagation from the V-shaped antenna, we reproduced the experimental results and revealed the existence of a protective zone.
我们利用时间分辨磁光克尔效应显微镜(TR-MOKE)研究了微图案坡莫合金薄膜中的自旋波动态。通过施加外部磁场,我们以皮秒级的分辨率观察到了自旋波信号的磁场依赖性。对信号的傅立叶变换分析证实了它们与色散关系的一致性,证明了利用 MOKE 技术成功地探测到了传播的自旋波。此外,我们还对 V 形天线产生的干涉自旋波进行了动态测量。实验结果显示,每个探测点的自旋波振幅存在差异。结合基于 V 形天线波传播的模拟分析,我们再现了实验结果,并揭示了保护区的存在。
{"title":"Spin-wave emission using a V-shaped antenna","authors":"Ryota Yoshida, Shoki Nezu and Koji Sekiguchi","doi":"10.35848/1347-4065/ad71d8","DOIUrl":"https://doi.org/10.35848/1347-4065/ad71d8","url":null,"abstract":"We investigated the dynamics of spin waves in micro-patterned Permalloy thin films using time-resolved magneto-optic Kerr effect microscopy (TR-MOKE). By applying an external magnetic field, we observe the field dependence of spin wave signals with picosecond resolution. Fourier transform analysis of the signals confirms their agreement with the dispersion relation, demonstrating the successful detection of propagating spin waves using the MOKE technique. Furthermore, we perform dynamic measurements of interfering spin waves generated by a V-shaped antenna. The experimental results reveal differences in spin wave amplitude at each detection point. In combination with simulation analysis based on wave propagation from the V-shaped antenna, we reproduced the experimental results and revealed the existence of a protective zone.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218098","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 : 2024-09-05DOI: 10.35848/1347-4065/ad6c58
Alexander Martin, Naho Kato, Tobias Fey, Kyle G. Webber, Ken-ichi Kakimoto
Ferroelectric ceramics based on x(Ba0.7Ca0.3)TiO3–(1−x)Ba(Zr0.2Ti0.8)O3 (BCZT100x) are regarded as promising lead-free candidates for piezoelectric applications. Heightened piezoelectric properties are found around specific temperatures, i.e. polymorphic phase boundaries. As broader thermal stability is required for certain applications, this study aims to increase the diffusiveness of the phase transitions by introducing ZrO2 as a filler material into a BCZT52 matrix. The diffuseness factor of the Curie point was evaluated and increased from approximately 1.60 to 1.88 with the addition of 4 vol% ZrO2 to BCZT52. As a result, samples with an additional 2 vol% showed the highest thermal stability in the temperature range between 25 °C and 70 °C. Here, the large signal piezoelectric strain coefficient