Plasma confinement was succeeded by an optoelectronic system with the aid of a vacuum ultraviolet (VUV) light source, called the photoemission-assisted plasma system. The photoemission-assisted plasma was generated by utilizing photoelectrons from the substrate cathode. The photoelectrons were emitted from the substrate by external VUV irradiation via the photoelectric effect and then worked as initial electrons triggering the plasma generation. The photoemission-assisted plasma was confined with bright luminescence in an argon atmosphere by controlling the flow rate and pressure. The plasma confinement survived at up to 6400 Pa, which was much higher than the pressure estimated from the current–voltage characteristics. These results suggested that the area exhibiting luminescence dominated by the γ regime becomes small as the argon flow rate increases; however, the area does not vanish because the VUV-excited photoelectrons are sufficiently supplied. The residual area is dominated by the α regime without luminescence. Thus, the photoemission-assisted plasma seems to be confined on the balance between α and γ regimes. Because the current in the α-regime area is one hundredth in magnitude compared with that in the γ-regime area, the actual current density results in over 40 times with strong luminescence. This confined plasma with certain voltage and current condition may be expected for developing a new plasma reaction system and for application in semiconductor engineering.
{"title":"Plasma confinement by an optoelectronic system","authors":"Ryuta Tsukazaki, Haruhiro Naito, Hisashi Koga, Akito Fukuda, Naoki Kato, Takayuki Watanabe, Susumu Takabayashi","doi":"10.1116/6.0003520","DOIUrl":"https://doi.org/10.1116/6.0003520","url":null,"abstract":"Plasma confinement was succeeded by an optoelectronic system with the aid of a vacuum ultraviolet (VUV) light source, called the photoemission-assisted plasma system. The photoemission-assisted plasma was generated by utilizing photoelectrons from the substrate cathode. The photoelectrons were emitted from the substrate by external VUV irradiation via the photoelectric effect and then worked as initial electrons triggering the plasma generation. The photoemission-assisted plasma was confined with bright luminescence in an argon atmosphere by controlling the flow rate and pressure. The plasma confinement survived at up to 6400 Pa, which was much higher than the pressure estimated from the current–voltage characteristics. These results suggested that the area exhibiting luminescence dominated by the γ regime becomes small as the argon flow rate increases; however, the area does not vanish because the VUV-excited photoelectrons are sufficiently supplied. The residual area is dominated by the α regime without luminescence. Thus, the photoemission-assisted plasma seems to be confined on the balance between α and γ regimes. Because the current in the α-regime area is one hundredth in magnitude compared with that in the γ-regime area, the actual current density results in over 40 times with strong luminescence. This confined plasma with certain voltage and current condition may be expected for developing a new plasma reaction system and for application in semiconductor engineering.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"30 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140677622","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}
As feature sizes continue to shrink for more advanced nodes, local critical dimension (CD) uniformity (LCDU) control becomes more critical than ever for improving defectivity, edge placement error, and yield enhancement. In this work, we developed a new approach utilizing an Ar plasma treatment with a direct current superposition function at low-temperature post patterning stack open. Our results demonstrated that this approach was capable of breaking the trade-off between CD shrink, LCDU improvement, and defectivity reduction. We significantly reduced the LCDU from 1.64 to 1.26 nm at the same CD level (∼10 nm). In contrast, no LCDU reduction was observed with the traditional CD shrink approach through trilayer process tuning. The mechanism for the LCDU improvement was investigated, and a hypothesis was proposed. We believe both the defect mitigation of the organic planarization layer profile and the vertical loading effect together with top sealing and in situ planarization contributed to the final LCDU improvement.
随着更先进节点的特征尺寸不断缩小，局部临界尺寸（CD）均匀性（LCDU）控制对于改善缺陷率、边缘贴装误差和提高成品率变得比以往任何时候都更为重要。在这项工作中，我们开发了一种新方法，利用氩等离子体处理和直流叠加功能，在低温后图案化堆栈打开。我们的研究结果表明，这种方法能够打破 CD 缩小、LCDU 改善和缺陷减少之间的权衡。在相同的 CD 水平（∼10 nm）下，我们将 LCDU 从 1.64 nm 大幅降至 1.26 nm。与此相反，通过三层工艺调整的传统 CD 收缩方法没有观察到 LCDU 的减少。我们对 LCDU 改善的机制进行了研究，并提出了一个假设。我们认为，有机平面化层剖面的缺陷缓解和垂直加载效应以及顶部密封和原位平面化共同促成了最终的 LCDU 改善。
{"title":"New approach of local critical dimension uniformity improvement for via/contact hole etch with direct current superposition","authors":"Emilia W. Hirsch, Dominik Metzler, Peng Wang","doi":"10.1116/6.0003464","DOIUrl":"https://doi.org/10.1116/6.0003464","url":null,"abstract":"As feature sizes continue to shrink for more advanced nodes, local critical dimension (CD) uniformity (LCDU) control becomes more critical than ever for improving defectivity, edge placement error, and yield enhancement. In this work, we developed a new approach utilizing an Ar plasma treatment with a direct current superposition function at low-temperature post patterning stack open. Our results demonstrated that this approach was capable of breaking the trade-off between CD shrink, LCDU improvement, and defectivity reduction. We significantly reduced the LCDU from 1.64 to 1.26 nm at the same CD level (∼10 nm). In contrast, no LCDU reduction was observed with the traditional CD shrink approach through trilayer process tuning. The mechanism for the LCDU improvement was investigated, and a hypothesis was proposed. We believe both the defect mitigation of the organic planarization layer profile and the vertical loading effect together with top sealing and in situ planarization contributed to the final LCDU improvement.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":" 33","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140684041","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}
A. Ayari, P. Vincent, S. Perisanu, Philippe Poncharal, S. Purcell
{"title":"Erratum: “All field emission experiments are noisy, … are any meaningful?” [J. Vac. Sci. Technol. B 41, 024001 (2023)]","authors":"A. Ayari, P. Vincent, S. Perisanu, Philippe Poncharal, S. Purcell","doi":"10.1116/6.0003654","DOIUrl":"https://doi.org/10.1116/6.0003654","url":null,"abstract":"","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140685893","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}
V. Timofeev, Ilya Skvortsov, V. Mashanov, Alexander Nikiforov, D. Kolyada, D. Firsov, Oleg Komkov, Samir Samadov, Alexey Sidorin, Oleg Orlov
Effects of postgrowth high-temperature annealing on vacancy complexes and photoluminescence (PL) from GeSiSn/Si multiple quantum wells (MQWs) are studied. The series of PL peaks related to the vacancy-tin complexes was observed for as-grown samples including different structures, such as GeSiSn/Si MQWs, multilayer periodic structure with GeSiSn quantum dots (QDs), GeSn cross-structures upon GeSiSn/Si MQWs, and thick GeSiSn layers. The PL band intensity is significantly reduced after annealing at 700 °C corresponding to the reduction in vacancy density, as demonstrated by the positron annihilation spectroscopy (PAS) data. Such annealing also results in the appearance of the PL signal related to the interband optical transitions in GeSiSn/Si MQWs. However, the high temperature could negatively impact the sharpness of heterointerfaces due to Sn diffusion, thus limiting the PL efficiency. To improve the luminescence properties of GeSiSn/Si structures, we proposed a two-stage technique combining both the annealing and subsequent treatment of samples in a hydrogen plasma at 200 °C. The plasma treatment significantly reduces the PL band of vacancy-related defects, whereas annealing at a moderate temperature of ∼600 °C prevents the blurring of heterointerfaces. As a result, we demonstrate an increase in the relative efficiency of interband PL of type II GeSiSn/Si MQW structures emitting in the range of 1.5–2 μm.
{"title":"Effects of high-temperature annealing on vacancy complexes and luminescence properties in multilayer periodic structures with elastically strained GeSiSn layers","authors":"V. Timofeev, Ilya Skvortsov, V. Mashanov, Alexander Nikiforov, D. Kolyada, D. Firsov, Oleg Komkov, Samir Samadov, Alexey Sidorin, Oleg Orlov","doi":"10.1116/6.0003557","DOIUrl":"https://doi.org/10.1116/6.0003557","url":null,"abstract":"Effects of postgrowth high-temperature annealing on vacancy complexes and photoluminescence (PL) from GeSiSn/Si multiple quantum wells (MQWs) are studied. The series of PL peaks related to the vacancy-tin complexes was observed for as-grown samples including different structures, such as GeSiSn/Si MQWs, multilayer periodic structure with GeSiSn quantum dots (QDs), GeSn cross-structures upon GeSiSn/Si MQWs, and thick GeSiSn layers. The PL band intensity is significantly reduced after annealing at 700 °C corresponding to the reduction in vacancy density, as demonstrated by the positron annihilation spectroscopy (PAS) data. Such annealing also results in the appearance of the PL signal related to the interband optical transitions in GeSiSn/Si MQWs. However, the high temperature could negatively impact the sharpness of heterointerfaces due to Sn diffusion, thus limiting the PL efficiency. To improve the luminescence properties of GeSiSn/Si structures, we proposed a two-stage technique combining both the annealing and subsequent treatment of samples in a hydrogen plasma at 200 °C. The plasma treatment significantly reduces the PL band of vacancy-related defects, whereas annealing at a moderate temperature of ∼600 °C prevents the blurring of heterointerfaces. As a result, we demonstrate an increase in the relative efficiency of interband PL of type II GeSiSn/Si MQW structures emitting in the range of 1.5–2 μm.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"11 s2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140693293","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}
In the field of integrated circuits, electron beam images can provide process parameter information such as linewidth and line spacing. However, this size information only accounts for a small proportion of the information that the image can provide. To maximize the information obtained from electron beam images, this paper proposes a three-dimensional reconstruction method based on the electron beam imaging model. This method reveals the relationship between the top-view scanning electron microscopy (SEM) image and the actual three-dimensional structure. And then, an iterative optimization method is used to optimize the model and structure parameters for 3D reconstructions. During optimization flow, the correlation between the real SEM image and the reconstructed image is used to build the cost function. Two-micrometer silicon structures, vertical edge, and rounded sidewall structures are applied to model verification. Results show that the proposed model, with a fitting correlation over 99.3% and edge-angle mismatch within 1°, does well in rebuilding both structures. Our method makes it possible for high-precision 3D profile metrology and defect inspection.
在集成电路领域，电子束图像可以提供线宽和线间距等工艺参数信息。然而，这些尺寸信息只占图像所能提供信息的一小部分。为了最大限度地利用电子束图像所提供的信息，本文提出了一种基于电子束成像模型的三维重建方法。该方法揭示了顶视扫描电子显微镜（SEM）图像与实际三维结构之间的关系。然后，采用迭代优化方法对模型和结构参数进行优化，以实现三维重建。在优化过程中，实际 SEM 图像与重建图像之间的相关性被用来建立成本函数。两微米硅结构、垂直边缘和圆形侧壁结构被应用于模型验证。结果表明，提出的模型拟合相关性超过 99.3%，边缘角度不匹配度在 1° 以内，在重建这两种结构方面表现良好。我们的方法使高精度三维轮廓计量和缺陷检测成为可能。
{"title":"Method to reconstruct three-dimensional profile based on top-view SEM images","authors":"Shuang Liu, Ge Liu, Hao Shen, Dinghai Rui, Libin Zhang, Yayi Wei","doi":"10.1116/6.0003471","DOIUrl":"https://doi.org/10.1116/6.0003471","url":null,"abstract":"In the field of integrated circuits, electron beam images can provide process parameter information such as linewidth and line spacing. However, this size information only accounts for a small proportion of the information that the image can provide. To maximize the information obtained from electron beam images, this paper proposes a three-dimensional reconstruction method based on the electron beam imaging model. This method reveals the relationship between the top-view scanning electron microscopy (SEM) image and the actual three-dimensional structure. And then, an iterative optimization method is used to optimize the model and structure parameters for 3D reconstructions. During optimization flow, the correlation between the real SEM image and the reconstructed image is used to build the cost function. Two-micrometer silicon structures, vertical edge, and rounded sidewall structures are applied to model verification. Results show that the proposed model, with a fitting correlation over 99.3% and edge-angle mismatch within 1°, does well in rebuilding both structures. Our method makes it possible for high-precision 3D profile metrology and defect inspection.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":" 54","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140692239","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}
Fabrication of high aspect ratio silicon nanopillars is challenging for various applications. A cryogenic silicon etching process using SF6 and O2 plasma is investigated to create silicon nanopillars with 10 μm height and tens of nanometers apex. In the process, fluorine radicals react with silicon atoms, releasing volatile SiFx byproducts and then oxygen atoms interact with SiFx and deposit a SiOxFy film acting as an inhibitor. By adjusting the O2 concentration and the forward radio frequency power, this process modifies the formation of the SiOxFy passivation film and adjusts the bombardment of ions onto the inhibitor, resulting in the desired positive taper angles of silicon pillars. Two etching steps, with higher and lower O2 concentrations, are consecutively combined to create a sharp apex and a wide base. The results demonstrate the high etching rate and controllability of cryogenic etching to obtain high aspect ratio silicon pillars with desired profiles.
{"title":"Cryogenic etching of positively tapered silicon pillars with controllable profiles","authors":"Xiaoli Zhu, Aixi Pan, Babak Shokouhi, Bo Cui","doi":"10.1116/6.0003372","DOIUrl":"https://doi.org/10.1116/6.0003372","url":null,"abstract":"Fabrication of high aspect ratio silicon nanopillars is challenging for various applications. A cryogenic silicon etching process using SF6 and O2 plasma is investigated to create silicon nanopillars with 10 μm height and tens of nanometers apex. In the process, fluorine radicals react with silicon atoms, releasing volatile SiFx byproducts and then oxygen atoms interact with SiFx and deposit a SiOxFy film acting as an inhibitor. By adjusting the O2 concentration and the forward radio frequency power, this process modifies the formation of the SiOxFy passivation film and adjusts the bombardment of ions onto the inhibitor, resulting in the desired positive taper angles of silicon pillars. Two etching steps, with higher and lower O2 concentrations, are consecutively combined to create a sharp apex and a wide base. The results demonstrate the high etching rate and controllability of cryogenic etching to obtain high aspect ratio silicon pillars with desired profiles.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"13 S18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140695105","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}
X. Jia, Yibo Wang, C. Fang, Bochang Li, Zhengdong Luo, Yan Liu, Yue Hao, Genquan Han
β-(AlxGa1−x)2O3/Ga2O3 modulation-doped field-effect transistors (MODFETs) with a dual-metal gate (DMG) architecture are designed, and the electrical characteristics of the DMG device are investigated in comparison with the single-metal gate (SMG) device by the Technology Computer-Aided Design (TCAD) simulation. The results demonstrate that the DMG MODFETs possess a superior transconductance (gm), current gain cut-off frequency (fT), and power gain cut-off frequency (fMAX) than those of SMG transistors, which is attributed to the regulated channel electric field by a DMG structure. With a gate length of 0.1 μm, the peak values of fT/fMAX of the designed DMG MODFET are obtained as 48.6/50.6 GHz, respectively. Moreover, a comprehensive thermal analysis is conducted between the SMG and DMG devices under steady-state and transient conditions. The DMG MODFET exhibits a lower maximum temperature than the SMG counterpart due to the reduced channel electric field, each subjected to the same power dissipation. This finding underscores the potential of the β-(AlxGa1−x)2O3/Ga2O3 MODFET with the DMG architecture as a promising approach for high-power radio frequency operations.
{"title":"Characteristics of β-(AlxGa1−x)2O3/Ga2O3 dual-metal gate modulation-doped field-effect transistors simulated by TCAD","authors":"X. Jia, Yibo Wang, C. Fang, Bochang Li, Zhengdong Luo, Yan Liu, Yue Hao, Genquan Han","doi":"10.1116/6.0003502","DOIUrl":"https://doi.org/10.1116/6.0003502","url":null,"abstract":"β-(AlxGa1−x)2O3/Ga2O3 modulation-doped field-effect transistors (MODFETs) with a dual-metal gate (DMG) architecture are designed, and the electrical characteristics of the DMG device are investigated in comparison with the single-metal gate (SMG) device by the Technology Computer-Aided Design (TCAD) simulation. The results demonstrate that the DMG MODFETs possess a superior transconductance (gm), current gain cut-off frequency (fT), and power gain cut-off frequency (fMAX) than those of SMG transistors, which is attributed to the regulated channel electric field by a DMG structure. With a gate length of 0.1 μm, the peak values of fT/fMAX of the designed DMG MODFET are obtained as 48.6/50.6 GHz, respectively. Moreover, a comprehensive thermal analysis is conducted between the SMG and DMG devices under steady-state and transient conditions. The DMG MODFET exhibits a lower maximum temperature than the SMG counterpart due to the reduced channel electric field, each subjected to the same power dissipation. This finding underscores the potential of the β-(AlxGa1−x)2O3/Ga2O3 MODFET with the DMG architecture as a promising approach for high-power radio frequency operations.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"18 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696558","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}
D. D’Ubaldo, M. Sbroscia, V. C. Ficca, E. Stellino, A. Pasqualetti, D. Sentenac, J. Gargiulo, L. Francescon, L. Pinard, E. Placidi
This article presents a study on the performance degradation of amorphous silica mirrors coated with silica/tantala, commonly utilized in gravitational wave interferometry measurements. The primary objective is to understand the factors contributing to the reduced performance, specifically the heightened noise observed after prolonged use of the mirrors in a vacuum. In this article, SiO2/Ta2O5 multilayered coated sample mirrors underwent analysis through x-ray photoemission spectro-microscopy, atomic force microscopy, and Raman spectroscopy, before and after exposure to a contaminating vacuum environment. Our findings revealed the possible correlation between the deterioration in mirror performance and an upsurge in contaminant carbon and defect populations within the silicon dioxide structure.
本文介绍了对引力波干涉测量中常用的涂有二氧化硅/钽的无定形二氧化硅反射镜性能退化的研究。主要目的是了解导致性能下降的因素，特别是在真空中长期使用反射镜后观察到的噪声增大。本文通过 X 射线光发射光谱显微镜、原子力显微镜和拉曼光谱，对 SiO2/Ta2O5 多层镀膜样品反射镜暴露于污染真空环境前后的情况进行了分析。我们的研究结果表明，反射镜性能的下降与二氧化硅结构中污染物碳和缺陷群的激增之间可能存在关联。
{"title":"Study of defects population and contaminations in silica/tantala coated mirrors","authors":"D. D’Ubaldo, M. Sbroscia, V. C. Ficca, E. Stellino, A. Pasqualetti, D. Sentenac, J. Gargiulo, L. Francescon, L. Pinard, E. Placidi","doi":"10.1116/6.0003510","DOIUrl":"https://doi.org/10.1116/6.0003510","url":null,"abstract":"This article presents a study on the performance degradation of amorphous silica mirrors coated with silica/tantala, commonly utilized in gravitational wave interferometry measurements. The primary objective is to understand the factors contributing to the reduced performance, specifically the heightened noise observed after prolonged use of the mirrors in a vacuum. In this article, SiO2/Ta2O5 multilayered coated sample mirrors underwent analysis through x-ray photoemission spectro-microscopy, atomic force microscopy, and Raman spectroscopy, before and after exposure to a contaminating vacuum environment. Our findings revealed the possible correlation between the deterioration in mirror performance and an upsurge in contaminant carbon and defect populations within the silicon dioxide structure.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"107 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140709243","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}
Tingxu Chen, Tianming Li, Liu Yang, Hao Li, Haiyang Wang, Renjie Cheng, Jiaoyin Wang, Hao Zhou, B. Hu, Hao Fu
Graphite is the most commonly used large-area cathode material in the high-power vacuum electron device for its long life and good repetitive-frequency performance, but its particle size selection scheme has not been elucidated. Therefore, in the present work, the explosive electron emission properties of flake graphite large area explosive electron emission cathodes with varied particle sizes are studied. The 320 mesh flake graphite has a current delay reduction of 0.2–0.9 ns compared to other samples at the same peak voltage. According to the Murphy–Good equation, the emission performance of each sample during the priming stage was calculated, and the threshold characteristics of 320 mesh flake graphite were significantly better than the other samples. After the space charge limited current is formed, the plasma expansion rate of all samples is 1.2±0.2cm/μs with a difference not exceeding 4% between samples. Our research provides a strong basis for the selection of raw materials for graphite based large area explosive electron emission cathodes and contributes to the development of cross-field high-power vacuum devices.
{"title":"Experimental study of flake graphite large-area explosion electron emission cathode performance based on particle size discrepancy","authors":"Tingxu Chen, Tianming Li, Liu Yang, Hao Li, Haiyang Wang, Renjie Cheng, Jiaoyin Wang, Hao Zhou, B. Hu, Hao Fu","doi":"10.1116/6.0003373","DOIUrl":"https://doi.org/10.1116/6.0003373","url":null,"abstract":"Graphite is the most commonly used large-area cathode material in the high-power vacuum electron device for its long life and good repetitive-frequency performance, but its particle size selection scheme has not been elucidated. Therefore, in the present work, the explosive electron emission properties of flake graphite large area explosive electron emission cathodes with varied particle sizes are studied. The 320 mesh flake graphite has a current delay reduction of 0.2–0.9 ns compared to other samples at the same peak voltage. According to the Murphy–Good equation, the emission performance of each sample during the priming stage was calculated, and the threshold characteristics of 320 mesh flake graphite were significantly better than the other samples. After the space charge limited current is formed, the plasma expansion rate of all samples is 1.2±0.2cm/μs with a difference not exceeding 4% between samples. Our research provides a strong basis for the selection of raw materials for graphite based large area explosive electron emission cathodes and contributes to the development of cross-field high-power vacuum devices.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140716758","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}
Crystalline thin films of LiGa5O8 have recently been realized through epitaxial growth via mist-chemical vapor deposition. The single crystal, spinel cubic LiGa5O8 films show promising fundamental material properties and, therefore, make LiGa5O8 a potential enabling material for power electronics. In this work, chemical resistance and etch susceptibility were investigated for the first time on crystalline LiGa5O8 thin films with various wet chemistries. It was found that LiGa5O8 is very chemically resistive to acid solutions, with no apparent etching effects observed when placed in concentrated acid solutions of HCl, H2SO4, HF, or H3PO4 at room temperature. In contrast, orthorhombic (010) LiGaO2 shows effective etching in HCl solutions at varying dilution concentrations, with etch rates measured between 8.6 [1000:1 (DI water: HCl concentration)] and 6092 nm/min (37 wt. % HCl). The inductively coupled plasma reactive ion etching (ICP-RIE) of LiGa5O8 using BCl3/Ar and CF4/Ar/O2 gas chemistries was investigated. The etching rate and surface morphology of etched surfaces were examined as a function of RIE and ICP power. Using a CF4/Ar/O2 gas chemistry with an RIE power of 75 W and an ICP power of 300 W resulted in smooth etched planar surfaces while maintaining an etch rate of ∼24.6 nm/min. Similar dry etching studies were performed for LiGaO2. It was found that the BCl3/Ar gas chemistry was better suited for LiGaO2 etching, with similar surface morphology quality being obtained after etching as prior etching when a RIE power of 15 W and an ICP power of 400 W is utilized.
{"title":"Wet and dry etching of ultrawide bandgap LiGa5O8 and LiGaO2","authors":"Vijaygopal Thirupakuzi Vangipuram, Kaitian Zhang, Hongping Zhao","doi":"10.1116/6.0003450","DOIUrl":"https://doi.org/10.1116/6.0003450","url":null,"abstract":"Crystalline thin films of LiGa5O8 have recently been realized through epitaxial growth via mist-chemical vapor deposition. The single crystal, spinel cubic LiGa5O8 films show promising fundamental material properties and, therefore, make LiGa5O8 a potential enabling material for power electronics. In this work, chemical resistance and etch susceptibility were investigated for the first time on crystalline LiGa5O8 thin films with various wet chemistries. It was found that LiGa5O8 is very chemically resistive to acid solutions, with no apparent etching effects observed when placed in concentrated acid solutions of HCl, H2SO4, HF, or H3PO4 at room temperature. In contrast, orthorhombic (010) LiGaO2 shows effective etching in HCl solutions at varying dilution concentrations, with etch rates measured between 8.6 [1000:1 (DI water: HCl concentration)] and 6092 nm/min (37 wt. % HCl). The inductively coupled plasma reactive ion etching (ICP-RIE) of LiGa5O8 using BCl3/Ar and CF4/Ar/O2 gas chemistries was investigated. The etching rate and surface morphology of etched surfaces were examined as a function of RIE and ICP power. Using a CF4/Ar/O2 gas chemistry with an RIE power of 75 W and an ICP power of 300 W resulted in smooth etched planar surfaces while maintaining an etch rate of ∼24.6 nm/min. Similar dry etching studies were performed for LiGaO2. It was found that the BCl3/Ar gas chemistry was better suited for LiGaO2 etching, with similar surface morphology quality being obtained after etching as prior etching when a RIE power of 15 W and an ICP power of 400 W is utilized.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"35 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140727630","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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