C. Verona, G. Verona Rinati, Giuseppe Schettino, G. Parisi
The interest in microdosimetry is growing thanks to the advancement in microdosimetric technologies, improving detector performance and reliability. Herein, the fabrication and characterization of a novel diamond‐based microdosimeter are proposed. The microdosimeter consists of an array of single‐crystal diamond Schottky diodes about 1.5 μm thick connected in parallel. The detector prototypes are characterized using the ion beam‐induced charge technique, employing a 6 MeV carbon ions microbeam. Despite a good overall response, the first prototypes are affected by the “bridge effect”: a charge collection beneath the metallic bridges connecting the sensitive volumes (SVs), which alters the energy deposition spectrum. To mitigate the bridge effect, different technological solutions are explored: the selective growth of intrinsic diamond layers and the use of an insulating material such as photoresist. These second prototypes reveal a good SV spatial definition without any charge collection from the bridges and a good response homogeneity within the SVs ranging between 3% and 5% full‐width‐half‐maximum among the different prototypes. While the cell‐like thickness and lateral dimensions of SVs make the diamond microdosimeter array ideal for radiobiological applications, its array configuration can make it highly versatile to perform under different fluence rate conditions in particle therapy.
{"title":"Development and Fabrication of Microdosimeter Arrays Based on Single‐Crystal Diamond Schottky Diodes","authors":"C. Verona, G. Verona Rinati, Giuseppe Schettino, G. Parisi","doi":"10.1002/pssa.202300987","DOIUrl":"https://doi.org/10.1002/pssa.202300987","url":null,"abstract":"The interest in microdosimetry is growing thanks to the advancement in microdosimetric technologies, improving detector performance and reliability. Herein, the fabrication and characterization of a novel diamond‐based microdosimeter are proposed. The microdosimeter consists of an array of single‐crystal diamond Schottky diodes about 1.5 μm thick connected in parallel. The detector prototypes are characterized using the ion beam‐induced charge technique, employing a 6 MeV carbon ions microbeam. Despite a good overall response, the first prototypes are affected by the “bridge effect”: a charge collection beneath the metallic bridges connecting the sensitive volumes (SVs), which alters the energy deposition spectrum. To mitigate the bridge effect, different technological solutions are explored: the selective growth of intrinsic diamond layers and the use of an insulating material such as photoresist. These second prototypes reveal a good SV spatial definition without any charge collection from the bridges and a good response homogeneity within the SVs ranging between 3% and 5% full‐width‐half‐maximum among the different prototypes. While the cell‐like thickness and lateral dimensions of SVs make the diamond microdosimeter array ideal for radiobiological applications, its array configuration can make it highly versatile to perform under different fluence rate conditions in particle therapy.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141371488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Löhnert, Arne Bochmann, Ahmed Ibrahim, J. Töpfer
By alternately stacking layers of two materials that differ in their Seebeck coefficient and electrical and thermal conductivity, a composite material with artificial anisotropy of thermal and electrical transport properties is formed. Due to the transverse Seebeck effect, a thermoelectric (TE) voltage is generated perpendicular to a temperature gradient ΔT, that is applied at a certain angle φ with respect to the stacked layers (0° < φ < 90°). The TE properties of layered artificial anisotropic materials are described analytically using existing concepts and extending the available definitions to develop a consistent image of anisotropic media for TE energy generation. Based on these analytical descriptions, the TE performance of ceramic oxide–metal composites and transverse TE generators (TTEG) made of them are numerically calculated and presented in contour plots. These so‐called micro‐ and macro‐Babin plots map the influence of internal geometric parameters, i.e., the layer thickness ratio and the angle φ of the applied temperature gradient with respect to the stacked layers. Based on these diagrams, the optimal TTEG geometry can be narrowed down in a simple and fast way. In addition, the diagrams are used for a material screening to evaluate the suitability of different oxide ceramics for use in a TTEG.
通过交替堆叠两种塞贝克系数、导电率和导热率不同的材料层，可以形成一种具有人工各向异性热传导和电传导特性的复合材料。由于横向塞贝克效应，在垂直于温度梯度 ΔT 的方向上产生热电（TE）电压，该温度梯度与堆叠层成一定角度 φ （0° < φ < 90°）。利用现有概念和扩展现有定义，对层状人工各向异性材料的 TE 特性进行了分析描述，从而为 TE 能量生成建立了各向异性介质的一致形象。在这些分析描述的基础上，对陶瓷氧化物-金属复合材料和由其制成的横向 TE 发电机 (TTEG) 的 TE 性能进行了数值计算，并以等值线图的形式呈现。这些所谓的微观和宏观巴宾图反映了内部几何参数的影响，即层厚比和外加温度梯度与堆叠层的夹角φ。根据这些图表，可以简单快速地缩小最佳 TTEG 几何形状的范围。此外，这些图表还可用于材料筛选，以评估不同氧化物陶瓷在 TTEG 中的适用性。
{"title":"Assessment of Artificial Anisotropic Materials for Transverse Thermoelectric Generators","authors":"R. Löhnert, Arne Bochmann, Ahmed Ibrahim, J. Töpfer","doi":"10.1002/pssa.202400321","DOIUrl":"https://doi.org/10.1002/pssa.202400321","url":null,"abstract":"\u0000By alternately stacking layers of two materials that differ in their Seebeck coefficient and electrical and thermal conductivity, a composite material with artificial anisotropy of thermal and electrical transport properties is formed. Due to the transverse Seebeck effect, a thermoelectric (TE) voltage is generated perpendicular to a temperature gradient ΔT, that is applied at a certain angle φ with respect to the stacked layers (0° < φ < 90°). The TE properties of layered artificial anisotropic materials are described analytically using existing concepts and extending the available definitions to develop a consistent image of anisotropic media for TE energy generation. Based on these analytical descriptions, the TE performance of ceramic oxide–metal composites and transverse TE generators (TTEG) made of them are numerically calculated and presented in contour plots. These so‐called micro‐ and macro‐Babin plots map the influence of internal geometric parameters, i.e., the layer thickness ratio and the angle φ of the applied temperature gradient with respect to the stacked layers. Based on these diagrams, the optimal TTEG geometry can be narrowed down in a simple and fast way. In addition, the diagrams are used for a material screening to evaluate the suitability of different oxide ceramics for use in a TTEG.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuanlei Zhang, Xuanming Zhang, Zhiwei Sun, Weisheng Wang, Maoqing Ling, Zhijie Kong, Ye Liang, Jiudun Yan, Wen Liu
Herein, the electrical characteristics and Schottky barrier of Ni/Au and Ni/Ag contacts on the GaN/AlGaN/GaN heterojunction are investigated. Both contacts on the p‐GaN contact layer (Mg: ≈3 × 1019 cm−3) exhibit weak Schottky characteristics. The nonlinear current–voltage (I–V) characteristics are observed, leading to variations in contact resistance (RC) and sheet resistance (Rsh) with changing bias voltage. The Ni/Ag contact achieves a lower Schottky barrier height calculated by using the I–V method. Furthermore, when employing a p++‐GaN layer (Mg: ≈1 × 1020 cm−3) as the contact layer, the Ni/Ag contact forms an Ohmic contact without Schottky characteristics, achieving a satisfactory RC of 30.31 Ω mm. This result demonstrates its viability as a competitive candidate for p‐channel field‐effect transistors’ fabrication.
本文研究了氮化镓/氮化铝/氮化镓异质结上镍/金和镍/银触点的电气特性和肖特基势垒。p-GaN 接触层（镁：≈3 × 1019 cm-3）上的两个触点都表现出弱肖特基特性。观察到非线性电流-电压（I-V）特性，导致接触电阻（RC）和薄片电阻（Rsh）随偏置电压变化而变化。使用 I-V 方法计算出的镍/银触点肖特基势垒高度较低。此外，当使用 p++-GaN 层（镁：≈1 × 1020 cm-3）作为接触层时，镍/银触点形成了无肖特基特性的欧姆接触，达到了令人满意的 30.31 Ω mm RC。这一结果表明，它是制造 p 沟道场效应晶体管的一种有竞争力的候选材料。
{"title":"Comparative Analysis of Ni/Ag and Ni/Au Contacts on GaN/AlGaN/GaN Platform","authors":"Yuanlei Zhang, Xuanming Zhang, Zhiwei Sun, Weisheng Wang, Maoqing Ling, Zhijie Kong, Ye Liang, Jiudun Yan, Wen Liu","doi":"10.1002/pssa.202400046","DOIUrl":"https://doi.org/10.1002/pssa.202400046","url":null,"abstract":"Herein, the electrical characteristics and Schottky barrier of Ni/Au and Ni/Ag contacts on the GaN/AlGaN/GaN heterojunction are investigated. Both contacts on the p‐GaN contact layer (Mg: ≈3 × 1019 cm−3) exhibit weak Schottky characteristics. The nonlinear current–voltage (I–V) characteristics are observed, leading to variations in contact resistance (RC) and sheet resistance (Rsh) with changing bias voltage. The Ni/Ag contact achieves a lower Schottky barrier height calculated by using the I–V method. Furthermore, when employing a p++‐GaN layer (Mg: ≈1 × 1020 cm−3) as the contact layer, the Ni/Ag contact forms an Ohmic contact without Schottky characteristics, achieving a satisfactory RC of 30.31 Ω mm. This result demonstrates its viability as a competitive candidate for p‐channel field‐effect transistors’ fabrication.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas Kaltsounis, Mohammed El Amrani, David Plaza Arguello, Hala El Rammouz, Vishwajeet Maurya, M. Lafossas, Simona Torrengo, Helge Haas, Laurent Mendizabal, Alain Gueugnot, Denis Mariolle, Thomas Jalabert, Julien Buckley, Yvon Cordier, Matthew Charles
Localized epitaxy of gallium nitride (GaN) on silicon (Si) wafers is an efficient way to relax elastically the tensile stress generated in the GaN layer after growth, allowing epitaxy of thick layers for the fabrication of vertical power devices operating at high voltage. In this study, a 4.7 μm‐thick GaN layer is grown by metal–organic vapor phase epitaxy on 200 mm‐diameter Si wafers for the fabrication of quasi‐vertical Schottky and p‐n diodes. The uniformity of the doping concentration in the layer is mapped spatially by scanning spreading resistance microscopy, while scanning capacitance microscopy illustrates the differently doped regions in the p‐n diode. The net doping concentration is extracted by capacitance–voltage (C–V) measurements and it is found to be about 3 × 1016 cm−3. On a 140 μm‐diameter quasi‐vertical p‐n diode, destructive breakdown occurs at 402 V, with no periphery protection on the device, demonstrating that localized epitaxy of GaN on Si has great potential for vertical high‐power devices.
{"title":"Localized Epitaxial Growth of 402 V Breakdown Voltage Quasi‐Vertical GaN‐on‐Si p‐n Diode on 200 mm‐Diameter Wafers","authors":"Thomas Kaltsounis, Mohammed El Amrani, David Plaza Arguello, Hala El Rammouz, Vishwajeet Maurya, M. Lafossas, Simona Torrengo, Helge Haas, Laurent Mendizabal, Alain Gueugnot, Denis Mariolle, Thomas Jalabert, Julien Buckley, Yvon Cordier, Matthew Charles","doi":"10.1002/pssa.202400059","DOIUrl":"https://doi.org/10.1002/pssa.202400059","url":null,"abstract":"Localized epitaxy of gallium nitride (GaN) on silicon (Si) wafers is an efficient way to relax elastically the tensile stress generated in the GaN layer after growth, allowing epitaxy of thick layers for the fabrication of vertical power devices operating at high voltage. In this study, a 4.7 μm‐thick GaN layer is grown by metal–organic vapor phase epitaxy on 200 mm‐diameter Si wafers for the fabrication of quasi‐vertical Schottky and p‐n diodes. The uniformity of the doping concentration in the layer is mapped spatially by scanning spreading resistance microscopy, while scanning capacitance microscopy illustrates the differently doped regions in the p‐n diode. The net doping concentration is extracted by capacitance–voltage (C–V) measurements and it is found to be about 3 × 1016 cm−3. On a 140 μm‐diameter quasi‐vertical p‐n diode, destructive breakdown occurs at 402 V, with no periphery protection on the device, demonstrating that localized epitaxy of GaN on Si has great potential for vertical high‐power devices.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hayata Takahata, Tomoaki Kachi, Naoki Hamashima, Ryunosuke Oka, Hisanori Ishiguro, Tetsuya Takeuchi, S. Kamiyama, M. Iwaya, Y. Saito, K. Okuno
Herein, hole generation in a 60 nm thick polarization‐doped AlxGa1–xN (x = 0.9–0.35)‐graded layer with some Mg doping (5 × 1018 cm−3) is demonstrated by using a 10 nm thick heavily (1 × 1020 cm−3) Mg‐doped Al0.35Ga0.65N contact layer. First, light emission from a deep‐ultraviolet light‐emitting diode is observed with the AlxGa1–xN (x = 0.9–0.35)‐graded layer and the Al0.35Ga0.65N contact layer, indicating a vertical hole transport from the Al0.35Ga0.65N contact layer to the active region through the polarization‐doped AlGaN‐graded layer. Second, hole concentration, mobility, and resistivity values of the AlxGa1–xN (x = 0.9–0.35)‐graded layer and the Al0.35Ga0.65N contact layer are evaluated by Hall effect measurement. A hole concentration of 1.8 × 1018 cm−3 is clearly observed by removing the AlGaN contact layer (not underneath of electrodes) to minimize a parallel conduction. The hole concentration shows a very weak temperature dependence from room temperature down to 150 K, suggesting that the holes are generated by polarization doping. Hole generation in the fully strained AlxGa1–xN (x = 0.9–0.35)‐graded layer is directly evaluated by Hall effect measurement with the AlGaN contact layer just underneath the electrodes.
{"title":"Hole Generation in Polarization‐Doped AlxGa1–xN (x = 0.9–0.35)‐Graded Layer with Heavily Mg‐Doped Al0.35Ga0.65N Contact Layer for 275 nm Deep‐Ultraviolet Light‐Emitting Diode","authors":"Hayata Takahata, Tomoaki Kachi, Naoki Hamashima, Ryunosuke Oka, Hisanori Ishiguro, Tetsuya Takeuchi, S. Kamiyama, M. Iwaya, Y. Saito, K. Okuno","doi":"10.1002/pssa.202400054","DOIUrl":"https://doi.org/10.1002/pssa.202400054","url":null,"abstract":"Herein, hole generation in a 60 nm thick polarization‐doped AlxGa1–xN (x = 0.9–0.35)‐graded layer with some Mg doping (5 × 1018 cm−3) is demonstrated by using a 10 nm thick heavily (1 × 1020 cm−3) Mg‐doped Al0.35Ga0.65N contact layer. First, light emission from a deep‐ultraviolet light‐emitting diode is observed with the AlxGa1–xN (x = 0.9–0.35)‐graded layer and the Al0.35Ga0.65N contact layer, indicating a vertical hole transport from the Al0.35Ga0.65N contact layer to the active region through the polarization‐doped AlGaN‐graded layer. Second, hole concentration, mobility, and resistivity values of the AlxGa1–xN (x = 0.9–0.35)‐graded layer and the Al0.35Ga0.65N contact layer are evaluated by Hall effect measurement. A hole concentration of 1.8 × 1018 cm−3 is clearly observed by removing the AlGaN contact layer (not underneath of electrodes) to minimize a parallel conduction. The hole concentration shows a very weak temperature dependence from room temperature down to 150 K, suggesting that the holes are generated by polarization doping. Hole generation in the fully strained AlxGa1–xN (x = 0.9–0.35)‐graded layer is directly evaluated by Hall effect measurement with the AlGaN contact layer just underneath the electrodes.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141381582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heike Voss, Xenia Knigge, Dominik Knapic, Matthias Weise, M. Sahre, Andreas Hertwig, Alessio Sacco, Andrea Mario Rossi, J. Radnik, Kai Müller, K. Wasmuth, J. Krüger, A. W. Hassel, V. Hodoroaba, J. Bonse
Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone‐forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre‐ and postanodization for two different characteristic microspikes covered by nanometric laser‐induced periodic surface structures on Ti–6Al–4V upon irradiation with near‐infrared ps‐laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X‐ray diffraction, and micro‐Raman spectroscopy, as well as near‐surface chemical analyses by X‐ray photoelectron spectroscopy and hard X‐ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near‐surface oxidation that may affect the different cell growth behavior for pre‐ or postanodized medical implants.
最近的出版物表明，电化学阳极氧化的顺序（在激光加工步骤之前或之后）对骨形成成骨细胞的反应起着重要作用--这种作用可用于改善永久性牙科或可移动骨植入物。为了探索这些不同的表面功能，我们结合电化学阳极氧化前和阳极氧化后，在两组不同的激光通量和光束扫描参数下，用近红外 ps 激光脉冲（波长 1030 nm，脉冲持续时间≈1 ps，脉冲重复频率分别为 67 kHz 和 80 kHz）对 Ti-6Al-4V 上的纳米激光诱导周期性表面结构所覆盖的两种不同特征的微尖峰进行了形态、结构和化学特性分析。这项工作包括通过扫描电子显微镜和白光干涉显微镜进行形态和地形研究，通过 X 射线衍射和微拉曼光谱进行结构材料检查，以及通过 X 射线光电子能谱和硬 X 射线光电子能谱进行近表面化学分析。这些结果有助于确定平均激光烧蚀深度、评估尖峰几何形状和表面粗糙度参数，并为了解可能影响阳极氧化前或阳极氧化后医疗植入物不同细胞生长行为的近表面氧化提供了新的详细见解。
{"title":"Picosecond Laser Processing of Hierarchical Micro–Nanostructures on Titanium Alloy upon Pre‐ and Postanodization: Morphological, Structural, and Chemical Effects","authors":"Heike Voss, Xenia Knigge, Dominik Knapic, Matthias Weise, M. Sahre, Andreas Hertwig, Alessio Sacco, Andrea Mario Rossi, J. Radnik, Kai Müller, K. Wasmuth, J. Krüger, A. W. Hassel, V. Hodoroaba, J. Bonse","doi":"10.1002/pssa.202300920","DOIUrl":"https://doi.org/10.1002/pssa.202300920","url":null,"abstract":"Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone‐forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre‐ and postanodization for two different characteristic microspikes covered by nanometric laser‐induced periodic surface structures on Ti–6Al–4V upon irradiation with near‐infrared ps‐laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X‐ray diffraction, and micro‐Raman spectroscopy, as well as near‐surface chemical analyses by X‐ray photoelectron spectroscopy and hard X‐ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near‐surface oxidation that may affect the different cell growth behavior for pre‐ or postanodized medical implants.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ping Yang, Zenghui Yang, Shuairong Deng, Wei Zhao, Yi Ding, Yongqi Pan, Hang Zhou, Dechao Meng, Su-Huai Wei
Ceramic capacitors are widely used in radioactive environments and are known to take irradiation damages, but most of previous studies of its reliability focus on thermal or electrical issues, and much less is known about the microscopic mechanism of its irradiation damaging process. Herein, it is shown that the capacitance of ceramic capacitors can change significantly under continuous gamma‐ray irradiation. Moreover, it is noticed that ex situ measurements will underestimate the effect comparing with the in situ one. Herein, it is discovered that this difference is due to the gamma‐ray‐induced photoelectric field, which dissipate rapidly in ex situ measurements. While the impact of the photoelectric field on the capacitance can be seen in situ, due to the recombination of photogenerated carriers and annealing of defects after irradiation, ex situ measurements only account for a part of the irradiation damage. This discovery indicates that ex situ measurements, which are prevailing in irradiation damage studies, can miss critical information, and in situ measurements are necessary for revealing the mechanism of the process.
{"title":"Gamma‐Ray‐Induced Photoelectric Field Exacerbating Irradiation Damage in Ceramic Capacitors","authors":"Ping Yang, Zenghui Yang, Shuairong Deng, Wei Zhao, Yi Ding, Yongqi Pan, Hang Zhou, Dechao Meng, Su-Huai Wei","doi":"10.1002/pssa.202400306","DOIUrl":"https://doi.org/10.1002/pssa.202400306","url":null,"abstract":"Ceramic capacitors are widely used in radioactive environments and are known to take irradiation damages, but most of previous studies of its reliability focus on thermal or electrical issues, and much less is known about the microscopic mechanism of its irradiation damaging process. Herein, it is shown that the capacitance of ceramic capacitors can change significantly under continuous gamma‐ray irradiation. Moreover, it is noticed that ex situ measurements will underestimate the effect comparing with the in situ one. Herein, it is discovered that this difference is due to the gamma‐ray‐induced photoelectric field, which dissipate rapidly in ex situ measurements. While the impact of the photoelectric field on the capacitance can be seen in situ, due to the recombination of photogenerated carriers and annealing of defects after irradiation, ex situ measurements only account for a part of the irradiation damage. This discovery indicates that ex situ measurements, which are prevailing in irradiation damage studies, can miss critical information, and in situ measurements are necessary for revealing the mechanism of the process.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141267404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, there has been a surge of research interest in exploring solar cells based on Cu2ZnSn(S, Se)4 (CZTSSe) for enhanced efficiencies. Traditionally, CdS has served as the buffer layer in these solar cells. However, there is growing scientific exploration aimed at replacing CdS with alternative materials. This work focuses on leveraging a graded CZTSSe absorber layer alongside tungsten disulfide (WS2) 2D transition metal dichalcogenides. WS2 semiconductor as buffer layer is less price, low toxicity with high‐stability, and its performance is compared to that of CdS/CZTSSe solar cells. This comparative study aims to assess the efficacy of the WS2/CZTSSe structure as a potential alternative to the conventional CdS/CZTSSe configuration, with the overarching objective of enhancing overall solar cell efficiency. Initially, to demonstrate the accuracy of our simulated results, a comparison is made between the reported experimental data of CdS/CZTSSe and the simulated data. This numerical investigation utilizes solar cell capacitance simulator ‐1D software. The primary focus of this research is to evaluate the effects of varying thicknesses and doping densities of the absorber and buffer layers, as well as WS2, CdS, and CZTSSe defect densities, on Voc, Jsc, fill factor (FF), and power conversion efficiency. The aim is to achieve optimal device performance through systematic optimization of these parameters. The findings reveal that the WS2/CZTSSe solar cell achieves the highest conversion efficiency of 14.38%, accompanied by a Voc of 0.6920 V, Jsc of 24.96 mA cm−2, and FF of 83.28%. This performance surpasses that of the CdS/CZTSSe configuration, which demonstrates an efficiency of 12.74%, Voc of 0.518 V, Jsc of 37.77 mA cm−2, and FF of 65.10%. These results hold significant promise for the practical implementation of WS2/CZTSSe solar cell structures, offering a pathway toward generating clean, pollution‐free, and cost‐effective energy solutions.
{"title":"Numerical Study of Graded CZT (S, Se) Solar Cell with 2D Transition Metal Dichalcogenide Tungsten Disulfide (WS2) as a Buffer Layer","authors":"Mohamed Lahoual, Mohammed Bourennane, L. Aidaoui","doi":"10.1002/pssa.202400250","DOIUrl":"https://doi.org/10.1002/pssa.202400250","url":null,"abstract":"Recently, there has been a surge of research interest in exploring solar cells based on Cu2ZnSn(S, Se)4 (CZTSSe) for enhanced efficiencies. Traditionally, CdS has served as the buffer layer in these solar cells. However, there is growing scientific exploration aimed at replacing CdS with alternative materials. This work focuses on leveraging a graded CZTSSe absorber layer alongside tungsten disulfide (WS2) 2D transition metal dichalcogenides. WS2 semiconductor as buffer layer is less price, low toxicity with high‐stability, and its performance is compared to that of CdS/CZTSSe solar cells. This comparative study aims to assess the efficacy of the WS2/CZTSSe structure as a potential alternative to the conventional CdS/CZTSSe configuration, with the overarching objective of enhancing overall solar cell efficiency. Initially, to demonstrate the accuracy of our simulated results, a comparison is made between the reported experimental data of CdS/CZTSSe and the simulated data. This numerical investigation utilizes solar cell capacitance simulator ‐1D software. The primary focus of this research is to evaluate the effects of varying thicknesses and doping densities of the absorber and buffer layers, as well as WS2, CdS, and CZTSSe defect densities, on Voc, Jsc, fill factor (FF), and power conversion efficiency. The aim is to achieve optimal device performance through systematic optimization of these parameters. The findings reveal that the WS2/CZTSSe solar cell achieves the highest conversion efficiency of 14.38%, accompanied by a Voc of 0.6920 V, Jsc of 24.96 mA cm−2, and FF of 83.28%. This performance surpasses that of the CdS/CZTSSe configuration, which demonstrates an efficiency of 12.74%, Voc of 0.518 V, Jsc of 37.77 mA cm−2, and FF of 65.10%. These results hold significant promise for the practical implementation of WS2/CZTSSe solar cell structures, offering a pathway toward generating clean, pollution‐free, and cost‐effective energy solutions.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shogo Fukushige, Y. Matsuda, M. Funato, Y. Kawakami
InGaN quantum wells (QWs) are grown at different temperatures on convex lens‐shaped GaN microstructures formed on the () plane. Microlens QWs grown at different temperatures have centrosymmetric convex lens shapes, and the wavelength spatial distributions within the structures exhibit similar tendencies. However, lowering the growth temperature broadens the wavelength range of room‐temperature cathodoluminescence spectra from the microlens QWs as ≈70 nm for ≈700 °C, ≈100 nm for ≈660 °C, and ≈150 nm for ≈650 °C. Peak wavelength profiles of the two orthogonal lines along [] and [] indicate that the broader emission bands are mainly due to the significant spatial distribution of the emission wavelength along the [] direction. Because the QW thickness variations are nearly the same along [] and [], the observed difference in the emission wavelength distributions along those directions is attributed to the difference in In incorporation, which is determined by the competition among the growth rate, crystal orientation, and growth temperature.
{"title":"An Approach Toward Broader Emission Bands in Semipolar InGaN Quantum Wells on Convex Lens‐Shaped GaN Microstructures via Lower‐Temperature Growth","authors":"Shogo Fukushige, Y. Matsuda, M. Funato, Y. Kawakami","doi":"10.1002/pssa.202400110","DOIUrl":"https://doi.org/10.1002/pssa.202400110","url":null,"abstract":"InGaN quantum wells (QWs) are grown at different temperatures on convex lens‐shaped GaN microstructures formed on the () plane. Microlens QWs grown at different temperatures have centrosymmetric convex lens shapes, and the wavelength spatial distributions within the structures exhibit similar tendencies. However, lowering the growth temperature broadens the wavelength range of room‐temperature cathodoluminescence spectra from the microlens QWs as ≈70 nm for ≈700 °C, ≈100 nm for ≈660 °C, and ≈150 nm for ≈650 °C. Peak wavelength profiles of the two orthogonal lines along [] and [] indicate that the broader emission bands are mainly due to the significant spatial distribution of the emission wavelength along the [] direction. Because the QW thickness variations are nearly the same along [] and [], the observed difference in the emission wavelength distributions along those directions is attributed to the difference in In incorporation, which is determined by the competition among the growth rate, crystal orientation, and growth temperature.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141388845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Behrad Radfar, Xiaolong Liu, Y. Berencén, M. S. Shaikh, S. Prucnal, U. Kentsch, V. Vähänissi, Shengqiang Zhou, H. Savin
Nanostructured silicon can reduce reflectance loss in optoelectronic applications, but intrinsic silicon cannot absorb photons with energy below its 1.1 eV bandgap. However, incorporating a high concentration of dopants, i.e., hyperdoping, to nanostructured silicon is expected to bring broadband absorption ranging from UV to short‐wavelength IR (SWIR, <2500 nm). In this work, we prepare nanostructured silicon using cryogenic plasma etching, which is then hyperdoped with selenium (Se) through ion implantation. Besides sub‐bandgap absorption, ion implantation forms crystal damage, which can be recovered through flash lamp annealing. We study crystal damage and broadband (250–2500 nm) absorption from planar and nanostructured surfaces. We first show that nanostructures survive ion implantation hyperdoping and flash lamp annealing under optimized conditions. Secondly, we demonstrate that nanostructured silicon has a 15% higher sub‐bandgap absorption (1100–2500 nm) compared to its non‐hyperdoped nanostructure counterpart while maintaining 97% above‐bandgap absorption (250–1100 nm). Lastly, we simulate the sub‐bandgap absorption of hyperdoped Si nanostructures in a 2D model using the finite element method. Simulation results show that the sub‐bandgap absorption is mainly limited by the thickness of the hyperdoped layer rather than the height of nanostructures.
{"title":"Extended Infrared Absorption in Nanostructured Si Through Se Implantation and Flash Lamp Annealing","authors":"Behrad Radfar, Xiaolong Liu, Y. Berencén, M. S. Shaikh, S. Prucnal, U. Kentsch, V. Vähänissi, Shengqiang Zhou, H. Savin","doi":"10.1002/pssa.202400133","DOIUrl":"https://doi.org/10.1002/pssa.202400133","url":null,"abstract":"Nanostructured silicon can reduce reflectance loss in optoelectronic applications, but intrinsic silicon cannot absorb photons with energy below its 1.1 eV bandgap. However, incorporating a high concentration of dopants, i.e., hyperdoping, to nanostructured silicon is expected to bring broadband absorption ranging from UV to short‐wavelength IR (SWIR, <2500 nm). In this work, we prepare nanostructured silicon using cryogenic plasma etching, which is then hyperdoped with selenium (Se) through ion implantation. Besides sub‐bandgap absorption, ion implantation forms crystal damage, which can be recovered through flash lamp annealing. We study crystal damage and broadband (250–2500 nm) absorption from planar and nanostructured surfaces. We first show that nanostructures survive ion implantation hyperdoping and flash lamp annealing under optimized conditions. Secondly, we demonstrate that nanostructured silicon has a 15% higher sub‐bandgap absorption (1100–2500 nm) compared to its non‐hyperdoped nanostructure counterpart while maintaining 97% above‐bandgap absorption (250–1100 nm). Lastly, we simulate the sub‐bandgap absorption of hyperdoped Si nanostructures in a 2D model using the finite element method. Simulation results show that the sub‐bandgap absorption is mainly limited by the thickness of the hyperdoped layer rather than the height of nanostructures.","PeriodicalId":20150,"journal":{"name":"physica status solidi (a)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141273812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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