Jia Qi He, Dian Chun Ju, Wen Kai Zou, Tian Yi Lv, Chun Yu Chen, Hui Li, Zhuang Yi, Bo Wen Li
The electrolytes of lithium-ion batteries (LIBs) directly affect their performance, safety, and reliability. However, existing electrolytes are still limited in terms of safety, performance, and environmental friendliness, constraining further development and application of LIBs. Herein, novel electrolytes based on a deep eutectic solvent consisting of LiTFSI [lithium bis(trifluoromethane)sulfonylimide] and DMA(N,N'-dimethylacetamide) were developed for LIBs. The results from thermogravimetry analysis, infrared spectroscopy, Raman scattering, UV-visible NIR diffuse reflectance, optical and scanning electron microscopy, and electrochemistry all showed safe, nonflammable, nontoxic, and environmentally friendly electrolytes with good thermal stability, enhanced electrochemical stability, and excellent lithium-ion conductivity. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed electrolytes with rapid transport of lithium ions and stable electrochemical interface formation. The electrolytes showed good compatibility with the LiFePO4 cathode, effectively protecting the structure of the LiFePO4 electrode. The first discharge capacity of LiTFSI-DMA deep eutectic electrolyte reached as high as 156.6 mAh g−1, with a discharge capacity after 365 cycles at 1C current density reaching 142.6 mAh g−1 and a capacity retention rate of more than 91%. Overall, LiTFSI-DMA deep eutectic electrolytes with superior performance and compatibility have the potential as high-performance nonflammable electrolytes for improved LIBs.
锂离子电池（LIB）的电解质直接影响其性能、安全性和可靠性。然而，现有的电解质在安全性、性能和环保性方面仍有局限，制约了锂离子电池的进一步开发和应用。本文开发了基于 LiTFSI [双（三氟甲烷）磺酰亚胺锂] 和 DMA（N,N'-二甲基乙酰胺）组成的深共晶溶剂的新型电解质，用于锂离子电池。热重分析、红外光谱、拉曼散射、紫外可见近红外漫反射、光学显微镜和扫描电子显微镜以及电化学研究结果均表明，该电解质安全、不燃、无毒、环保，具有良好的热稳定性、更高的电化学稳定性和优异的锂离子传导性。循环伏安法和电化学阻抗谱证实，电解质能快速传输锂离子并形成稳定的电化学界面。电解质与磷酸铁锂阴极具有良好的相容性，有效地保护了磷酸铁锂电极的结构。LiTFSI-DMA 深共晶电解质的首次放电容量高达 156.6 mAh g-1，在 1C 电流密度下循环 365 次后的放电容量达到 142.6 mAh g-1，容量保持率超过 91%。总之，LiTFSI-DMA 深共晶电解质具有优异的性能和兼容性，有望成为改进型 LIB 的高性能不易燃电解质。
{"title":"Novel amide-based deep eutectic solvent electrolytes for high-performance lithium-ion batteries","authors":"Jia Qi He, Dian Chun Ju, Wen Kai Zou, Tian Yi Lv, Chun Yu Chen, Hui Li, Zhuang Yi, Bo Wen Li","doi":"10.1116/6.0003452","DOIUrl":"https://doi.org/10.1116/6.0003452","url":null,"abstract":"The electrolytes of lithium-ion batteries (LIBs) directly affect their performance, safety, and reliability. However, existing electrolytes are still limited in terms of safety, performance, and environmental friendliness, constraining further development and application of LIBs. Herein, novel electrolytes based on a deep eutectic solvent consisting of LiTFSI [lithium bis(trifluoromethane)sulfonylimide] and DMA(N,N'-dimethylacetamide) were developed for LIBs. The results from thermogravimetry analysis, infrared spectroscopy, Raman scattering, UV-visible NIR diffuse reflectance, optical and scanning electron microscopy, and electrochemistry all showed safe, nonflammable, nontoxic, and environmentally friendly electrolytes with good thermal stability, enhanced electrochemical stability, and excellent lithium-ion conductivity. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed electrolytes with rapid transport of lithium ions and stable electrochemical interface formation. The electrolytes showed good compatibility with the LiFePO4 cathode, effectively protecting the structure of the LiFePO4 electrode. The first discharge capacity of LiTFSI-DMA deep eutectic electrolyte reached as high as 156.6 mAh g−1, with a discharge capacity after 365 cycles at 1C current density reaching 142.6 mAh g−1 and a capacity retention rate of more than 91%. Overall, LiTFSI-DMA deep eutectic electrolytes with superior performance and compatibility have the potential as high-performance nonflammable electrolytes for improved LIBs.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"53 28","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141010069","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}
Ellipsometry is a well-known material analytical method widely used to measure thickness and optical properties of thin films and surfaces across a wide range of industrial and research applications including critical dimensions in chipmaking. The method employs the fact that light undergoes a change in polarization state upon reflection from or transmission through a material. The desired properties of the surface structure are related to measurements by the electromagnetic models expressed by Maxwell’s equations as well as models of material properties. The work here demonstrates the use of artificial intelligence in the form of a multilayer perceptron artificial neural network to apply the electromagnetic model. The reflecting surface examined here is composed of indium tin oxide (ITO) films approximately 400 nm in thickness deposited on silicon substrates. Solutions are provided by 299 artificial neural networks, one per wavelength from 210 to 1700 nm across which ITO exhibits transparent as well as absorbing characteristics. Thus, it serves as a proxy for a wide range of other materials. To train the network, simulated measurements are computed at two thicknesses which differ randomly by 1–6 nm and at three different incidence angles of 55°, 65°, and 75°. Following training, results are obtained in less than one second on a conventional desktop computer.
{"title":"Numerical ellipsometry: Artificial intelligence for rapid analysis of indium tin oxide films on silicon","authors":"F. Urban, D. Barton","doi":"10.1116/6.0003548","DOIUrl":"https://doi.org/10.1116/6.0003548","url":null,"abstract":"Ellipsometry is a well-known material analytical method widely used to measure thickness and optical properties of thin films and surfaces across a wide range of industrial and research applications including critical dimensions in chipmaking. The method employs the fact that light undergoes a change in polarization state upon reflection from or transmission through a material. The desired properties of the surface structure are related to measurements by the electromagnetic models expressed by Maxwell’s equations as well as models of material properties. The work here demonstrates the use of artificial intelligence in the form of a multilayer perceptron artificial neural network to apply the electromagnetic model. The reflecting surface examined here is composed of indium tin oxide (ITO) films approximately 400 nm in thickness deposited on silicon substrates. Solutions are provided by 299 artificial neural networks, one per wavelength from 210 to 1700 nm across which ITO exhibits transparent as well as absorbing characteristics. Thus, it serves as a proxy for a wide range of other materials. To train the network, simulated measurements are computed at two thicknesses which differ randomly by 1–6 nm and at three different incidence angles of 55°, 65°, and 75°. Following training, results are obtained in less than one second on a conventional desktop computer.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"10 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141005906","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}
The differences in properties between ceramic coatings and their alloy substrates are the main factor that affects the adhesion between the coating and the substrate. Therefore, it is necessary to design a transition layer between them. Gradient elastic modulus CrN (G-CrN) coatings with various thicknesses of the gradient elastic modulus transition layers (G-layer) were prepared on Ti6Al4 V titanium alloy (TC4) and W6Mo5Cr4V2 high-speed steel (W6) substrates by varying the reactive flows using the hot-wire plasma-enhanced magnetron sputtering technique. The results showed that the elastic modulus difference (ΔE) between W6 and the G-CrN coatings was smaller than that between G-CrN and TC4. The large ΔE resulted in an asynchrony of TC4’s plastic deformation and G-CrN’s elastic deformation, leading to a large interfacial tensile stress and surface strain under an impact load, and therefore poor G-CrN/TC4 adhesion. A thick G-layer, up to 0.9 μm, effectively compensated for the deformation asynchrony, and the G-CrN/TC4 adhesion improved to 80 N. The CrN/W6 adhesion remained excellent, beyond 100 N for G-CrN/W6 with a 0.2−0.9 μm thickness of the G-layers, because its ΔE was small and the deformation asynchrony was reduced. The mechanism of the poor coating-substrate adhesion was attributed to the deformation asynchrony caused by the large coating-substrate ΔE, which can be improved by a reasonably thick G-layer.
{"title":"Design principle of gradient elastic modulus transition layer via substrate mechanical property","authors":"Linfan Sun, Yi Ren, Biao Si, Yanwen Zhou","doi":"10.1116/6.0003673","DOIUrl":"https://doi.org/10.1116/6.0003673","url":null,"abstract":"The differences in properties between ceramic coatings and their alloy substrates are the main factor that affects the adhesion between the coating and the substrate. Therefore, it is necessary to design a transition layer between them. Gradient elastic modulus CrN (G-CrN) coatings with various thicknesses of the gradient elastic modulus transition layers (G-layer) were prepared on Ti6Al4 V titanium alloy (TC4) and W6Mo5Cr4V2 high-speed steel (W6) substrates by varying the reactive flows using the hot-wire plasma-enhanced magnetron sputtering technique. The results showed that the elastic modulus difference (ΔE) between W6 and the G-CrN coatings was smaller than that between G-CrN and TC4. The large ΔE resulted in an asynchrony of TC4’s plastic deformation and G-CrN’s elastic deformation, leading to a large interfacial tensile stress and surface strain under an impact load, and therefore poor G-CrN/TC4 adhesion. A thick G-layer, up to 0.9 μm, effectively compensated for the deformation asynchrony, and the G-CrN/TC4 adhesion improved to 80 N. The CrN/W6 adhesion remained excellent, beyond 100 N for G-CrN/W6 with a 0.2−0.9 μm thickness of the G-layers, because its ΔE was small and the deformation asynchrony was reduced. The mechanism of the poor coating-substrate adhesion was attributed to the deformation asynchrony caused by the large coating-substrate ΔE, which can be improved by a reasonably thick G-layer.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"41 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141010378","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}
Qinzhen Hao, M. A. I. Elgarhy, Pilbum Kim, Sang Ki Nam, Song-Yun Kang, Vincent M. Donnelly
Atomic layer etching of Si is reported in a radio frequency (RF) pulsed-power inductively coupled (ICP) plasma, with periodic injections of HBr into a continuous He/Ar carrier gas flow, sometimes with trace added O2. Several pulsing schemes were investigated, with HBr injection simultaneous with or alternating with ICP power. The product removal step was induced by applying RF power to the substrate, in sync with ICP power. Etching and dosing were monitored with optical emission spectroscopy. Little or no chemically enhanced ion-assisted etching was observed unless there was some overlap between HBr in the chamber and ICP power. This indicates that HBr dissociative chemisorption deposits much less Br on Si, compared with that from Br created by dissociation of HBr in the ICP. Chemically assisted etching rates nearly saturate at 2.0 nm/cycle as a function of increasing HBr-containing ICP dose at −75 VDC substrate self-bias. The coupled effects of O2 addition and substrate self-bias DC voltage on the etching rate were also explored. Etching slowed or stopped with increasing O2 addition. As bias power was increased, more O2 could be added before etching stopped.
{"title":"Atomic layer etching in HBr/He/Ar/O2 plasmas","authors":"Qinzhen Hao, M. A. I. Elgarhy, Pilbum Kim, Sang Ki Nam, Song-Yun Kang, Vincent M. Donnelly","doi":"10.1116/6.0003593","DOIUrl":"https://doi.org/10.1116/6.0003593","url":null,"abstract":"Atomic layer etching of Si is reported in a radio frequency (RF) pulsed-power inductively coupled (ICP) plasma, with periodic injections of HBr into a continuous He/Ar carrier gas flow, sometimes with trace added O2. Several pulsing schemes were investigated, with HBr injection simultaneous with or alternating with ICP power. The product removal step was induced by applying RF power to the substrate, in sync with ICP power. Etching and dosing were monitored with optical emission spectroscopy. Little or no chemically enhanced ion-assisted etching was observed unless there was some overlap between HBr in the chamber and ICP power. This indicates that HBr dissociative chemisorption deposits much less Br on Si, compared with that from Br created by dissociation of HBr in the ICP. Chemically assisted etching rates nearly saturate at 2.0 nm/cycle as a function of increasing HBr-containing ICP dose at −75 VDC substrate self-bias. The coupled effects of O2 addition and substrate self-bias DC voltage on the etching rate were also explored. Etching slowed or stopped with increasing O2 addition. As bias power was increased, more O2 could be added before etching stopped.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"27 1‐2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141006614","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}
Current day x-ray photoelectron spectroscopy (XPS) instrument makers have made significant advances in charge compensation systems over the last 20 years, which makes it easier to analyze insulators, but samples still have many differences in chemistry, dielectric properties, sizes, surface roughness, etc. that force instrument operators to tweak flood gun settings if they want or need to obtain high quality chemical state spectra that provide the most information. This guide teaches which flood gun variables to check, and how to optimize electron flood gun settings by presenting high energy resolution, chemical state spectra that show the result of using a poorly aligned flood gun on modern XPS instruments equipped with a monochromatic aluminum Kalpha x-ray source. This guide is focused on the XPS measurement of insulators—nonconductive metal oxides and polymers. This guide shows that by measuring commonly available polymers (polypropylene and polyethylene terephthalate) or ceramic materials (SiO2 and Al2O3), the operator can easily characterize the good and bad effects of XY position settings and other settings provided by modern electron flood gun systems. This guide includes many original, never-before-published XPS peak full width at half maximum (FWHM) that will greatly assist peak-fitting efforts. This guide reveals a direct correlation between electron count-rate and best charge-control settings. This guide discusses sample and instrument issues that affect surface charging and explains how to check the quality of charge control by measuring the FWHM and binding energy of C (1s) or O (1s) spectra produced from the sample currently being analyzed. A list of other charge-control methods is provided, along with advice and a best-known method. The availability of large extensive databases of actual spectra is extremely beneficial to users who need real-world examples of high quality chemical state spectra to guide their in-house efforts to collect high quality spectra and to interpret valuable information from the peak-fits of those spectra.
在过去的 20 年中，当今的 X 射线光电子能谱 (XPS) 仪器制造商在电荷补偿系统方面取得了长足的进步，这使得分析绝缘体变得更加容易，但样品在化学性质、介电性质、尺寸、表面粗糙度等方面仍然存在许多差异，这迫使仪器操作人员在希望或需要获得高质量的化学态光谱以提供最多信息时，必须对淹没枪设置进行调整。本指南通过展示高能量分辨率的化学态光谱，说明了在配备单色铝卡尔法 X 射线源的现代 XPS 仪器上使用对准不良的淹没枪所产生的结果，从而介绍了应检查哪些淹没枪变量，以及如何优化电子淹没枪设置。本指南重点介绍绝缘体-不导电金属氧化物和聚合物的 XPS 测量。本指南显示，通过测量常见的聚合物（聚丙烯和聚对苯二甲酸乙二酯）或陶瓷材料（SiO2 和 Al2O3），操作人员可以轻松描述 XY 位置设置和现代电子枪系统提供的其他设置的好坏影响。本指南包含许多从未公开过的 XPS 峰值半最大值全宽（FWHM）原始数据，对峰值拟合工作大有帮助。本指南揭示了电子计数率与最佳电荷控制设置之间的直接关联。本指南讨论了影响表面电荷的样品和仪器问题，并解释了如何通过测量当前正在分析的样品所产生的 C (1s) 或 O (1s) 光谱的 FWHM 和结合能来检查电荷控制的质量。此外，还提供了一份其他电荷控制方法的清单，以及建议和一种最著名的方法。用户需要高质量化学态光谱的实际示例，以指导其内部收集高质量光谱的工作，并从这些光谱的峰值拟合中解读有价值的信息。
{"title":"XPS guide for insulators: Electron flood gun operation and optimization, surface charging, controlled charging, differential charging, useful FWHMs, problems and solutions, and advice","authors":"B. Vincent Crist","doi":"10.1116/6.0003439","DOIUrl":"https://doi.org/10.1116/6.0003439","url":null,"abstract":"Current day x-ray photoelectron spectroscopy (XPS) instrument makers have made significant advances in charge compensation systems over the last 20 years, which makes it easier to analyze insulators, but samples still have many differences in chemistry, dielectric properties, sizes, surface roughness, etc. that force instrument operators to tweak flood gun settings if they want or need to obtain high quality chemical state spectra that provide the most information. This guide teaches which flood gun variables to check, and how to optimize electron flood gun settings by presenting high energy resolution, chemical state spectra that show the result of using a poorly aligned flood gun on modern XPS instruments equipped with a monochromatic aluminum Kalpha x-ray source. This guide is focused on the XPS measurement of insulators—nonconductive metal oxides and polymers. This guide shows that by measuring commonly available polymers (polypropylene and polyethylene terephthalate) or ceramic materials (SiO2 and Al2O3), the operator can easily characterize the good and bad effects of XY position settings and other settings provided by modern electron flood gun systems. This guide includes many original, never-before-published XPS peak full width at half maximum (FWHM) that will greatly assist peak-fitting efforts. This guide reveals a direct correlation between electron count-rate and best charge-control settings. This guide discusses sample and instrument issues that affect surface charging and explains how to check the quality of charge control by measuring the FWHM and binding energy of C (1s) or O (1s) spectra produced from the sample currently being analyzed. A list of other charge-control methods is provided, along with advice and a best-known method. The availability of large extensive databases of actual spectra is extremely beneficial to users who need real-world examples of high quality chemical state spectra to guide their in-house efforts to collect high quality spectra and to interpret valuable information from the peak-fits of those spectra.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"27 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140658269","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 present study, hydrogenation treatment was adopted to tailor the phase constituents of the Ti-V-Al shape memory alloy, further optimizing its performances. It can be found that hydrogenation treatment induced the transition from the α″ martensite phase to the β parent phase. Moreover, large amounts of hydride precipitates can be observed in the hydrogenation treated Ti-V-Al shape memory alloy with longer time of 5h. Meanwhile, the grain size of the Ti-V-Al shape memory alloy was reduced as a result of hydrogenation treatment. The interstitial atom H serving as a β-stabilizing element led to the reduction of martensitic transformation temperature. In proportion, hydrogenation treatment caused the enhancement of yield strength and decrease of elastic modulus, which promoted its application in biomedical fields. Besides, by optimizing the time of hydrogenation treatment, the hydrogenation treated Ti-V-Al shape memory alloy with 1 h possessed the superior corrosion resistance.
本研究采用氢化处理来调整 Ti-V-Al 形状记忆合金的相组成，从而进一步优化其性能。研究发现，氢化处理诱导了从α″马氏体相向β母相的转变。此外，在氢化处理时间较长（5 小时）的 Ti-V-Al 形状记忆合金中可以观察到大量氢化物沉淀。同时，Ti-V-Al 形状记忆合金的晶粒尺寸因氢化处理而减小。间隙原子 H 作为一种 β 稳定元素，导致马氏体转变温度降低。与此同时，氢化处理还提高了屈服强度，降低了弹性模量，从而促进了其在生物医学领域的应用。此外，通过优化氢化处理时间，氢化处理 1 h 的 Ti-V-Al 形状记忆合金具有更优越的耐腐蚀性。
{"title":"Effect of high temperature thermohydrogen treatment on the microstructure, martensitic transformation, and mechanical and corrosion behaviors of Ti-V-Al lightweight shape memory alloy","authors":"Xiaoyang Yi, Wei Liu, Gaofeng Liu, Yunfei Wang, Weijian Li, Guohao Zhang, Yanqing Wu, Shangzhou Zhang, Hai-zhen Wang, B. Sun, Weihong Gao, Xianglong Meng, Zhiyong Gao","doi":"10.1116/6.0003550","DOIUrl":"https://doi.org/10.1116/6.0003550","url":null,"abstract":"In the present study, hydrogenation treatment was adopted to tailor the phase constituents of the Ti-V-Al shape memory alloy, further optimizing its performances. It can be found that hydrogenation treatment induced the transition from the α″ martensite phase to the β parent phase. Moreover, large amounts of hydride precipitates can be observed in the hydrogenation treated Ti-V-Al shape memory alloy with longer time of 5h. Meanwhile, the grain size of the Ti-V-Al shape memory alloy was reduced as a result of hydrogenation treatment. The interstitial atom H serving as a β-stabilizing element led to the reduction of martensitic transformation temperature. In proportion, hydrogenation treatment caused the enhancement of yield strength and decrease of elastic modulus, which promoted its application in biomedical fields. Besides, by optimizing the time of hydrogenation treatment, the hydrogenation treated Ti-V-Al shape memory alloy with 1 h possessed the superior corrosion resistance.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"62 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140664754","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}
Ankit Shrivastava, M. Kalaswad, Joyce O. Custer, David P. Adams, H. Najm
We introduce a Bayesian optimization approach to guide the sputter deposition of molybdenum thin films, aiming to achieve desired residual stress and sheet resistance while minimizing susceptibility to stochastic fluctuations during deposition. Thin films are pivotal in numerous technologies, including semiconductors and optical devices, where their properties are critical. Sputter deposition parameters, such as deposition power, vacuum chamber pressure, and working distance, influence physical properties like residual stress and resistance. Excessive stress and high resistance can impair device performance, necessitating the selection of optimal process parameters. Furthermore, these parameters should ensure the consistency and reliability of thin film properties, assisting in the reproducibility of the devices. However, exploring the multidimensional design space for process optimization is expensive. Bayesian optimization is ideal for optimizing inputs/parameters of general black-box functions without reliance on gradient information. We utilize Bayesian optimization to optimize deposition power and pressure using a custom-built objective function incorporating observed stress and resistance data. Additionally, we integrate prior knowledge of stress variation with pressure into the objective function to prioritize films least affected by stochastic variations. Our findings demonstrate that Bayesian optimization effectively explores the design space and identifies optimal parameter combinations meeting desired stress and resistance specifications.
{"title":"Bayesian optimization for stable properties amid processing fluctuations in sputter deposition","authors":"Ankit Shrivastava, M. Kalaswad, Joyce O. Custer, David P. Adams, H. Najm","doi":"10.1116/6.0003418","DOIUrl":"https://doi.org/10.1116/6.0003418","url":null,"abstract":"We introduce a Bayesian optimization approach to guide the sputter deposition of molybdenum thin films, aiming to achieve desired residual stress and sheet resistance while minimizing susceptibility to stochastic fluctuations during deposition. Thin films are pivotal in numerous technologies, including semiconductors and optical devices, where their properties are critical. Sputter deposition parameters, such as deposition power, vacuum chamber pressure, and working distance, influence physical properties like residual stress and resistance. Excessive stress and high resistance can impair device performance, necessitating the selection of optimal process parameters. Furthermore, these parameters should ensure the consistency and reliability of thin film properties, assisting in the reproducibility of the devices. However, exploring the multidimensional design space for process optimization is expensive. Bayesian optimization is ideal for optimizing inputs/parameters of general black-box functions without reliance on gradient information. We utilize Bayesian optimization to optimize deposition power and pressure using a custom-built objective function incorporating observed stress and resistance data. Additionally, we integrate prior knowledge of stress variation with pressure into the objective function to prioritize films least affected by stochastic variations. Our findings demonstrate that Bayesian optimization effectively explores the design space and identifies optimal parameter combinations meeting desired stress and resistance specifications.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"15 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660139","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}
Zon, Tzu-Wei Lo, Zhen-Lun Li, Samatcha Vorathamrong, Chao-Chia Cheng, Chun-Nien Liu, Chun-Te Chiang, Li-Wei Hung, Ming-Sen Hsu, Wei-Sheng Liu, Jen-Inn Chyi, Charles W. Tu
InGaAs/GaAsSb “W” quantum wells with GaAsP barriers are grown on GaAs (001) substrates by molecular beam epitaxy. We investigate the effect of the Sb composition in GaAsSb on the photoluminescence (PL) wavelength. X-ray rocking curve (XRC) measurements and simulations are performed to investigate the material composition and layer thickness. Low-temperature PL spectra are consistent with the XRC results. At the lowest Sb composition of 6%, the PL intensity is the strongest, and room-temperature PL is realized at ∼1100 nm. By increasing the Sb composition in the GaAsSb layer, low-temperature (20 K) PL emits at longer wavelength up to ∼1400 nm at 21% Sb while the PL intensity is the weakest. The XRC is also degraded. The strained bandgap simulation reveals the type-I to type-II band alignment transition as the Sb composition is ≥9%.
{"title":"Tuning the emission wavelength by varying the Sb composition in InGaAs/GaAsSb “W” quantum wells grown on GaAs (001) substrates","authors":"Zon, Tzu-Wei Lo, Zhen-Lun Li, Samatcha Vorathamrong, Chao-Chia Cheng, Chun-Nien Liu, Chun-Te Chiang, Li-Wei Hung, Ming-Sen Hsu, Wei-Sheng Liu, Jen-Inn Chyi, Charles W. Tu","doi":"10.1116/6.0003501","DOIUrl":"https://doi.org/10.1116/6.0003501","url":null,"abstract":"InGaAs/GaAsSb “W” quantum wells with GaAsP barriers are grown on GaAs (001) substrates by molecular beam epitaxy. We investigate the effect of the Sb composition in GaAsSb on the photoluminescence (PL) wavelength. X-ray rocking curve (XRC) measurements and simulations are performed to investigate the material composition and layer thickness. Low-temperature PL spectra are consistent with the XRC results. At the lowest Sb composition of 6%, the PL intensity is the strongest, and room-temperature PL is realized at ∼1100 nm. By increasing the Sb composition in the GaAsSb layer, low-temperature (20 K) PL emits at longer wavelength up to ∼1400 nm at 21% Sb while the PL intensity is the weakest. The XRC is also degraded. The strained bandgap simulation reveals the type-I to type-II band alignment transition as the Sb composition is ≥9%.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":" 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140685340","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}
Surface charging caused by the bombardment of samples with positive ion beams is a significant problem in material processing and surface analysis. The charging potential of an electrically isolated sample is commonly believed to increase with the acceleration voltage of a positive ion beam in the absence of charge compensation. Contrary to the common belief, however, this paper reports that the charging potential of an electrically isolated ionic liquid target decreases with increasing acceleration voltage of a positive cluster ion beam. A typical ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide (EMI-TFSA), was used as the target. It was placed on a metal plate that was electrically isolated from the ground, and its charging potential during cluster ion bombardment was measured with a high-impedance electrometer. For comparison, an electrically isolated metal plate was used. This study demonstrates that the charging potential varies significantly depending on cluster ion species and target materials. The charging potential of the metal plate increased monotonically with the irradiation time, whereas that of the ionic liquid target saturated at a lower voltage. The charging potential of the ionic liquid target decreased with increasing acceleration voltage of the ion beam even though the beam current increased. Larger cluster ions (m/z 502) caused less charge buildup than lighter cluster ions (m/z 111). The results obtained are explained by considering secondary ion emission from the ionic liquid target, which reduce the incoming net charge into the target, resulting in reduced surface charging.
{"title":"Significant decrease in surface charging of electrically isolated ionic liquid by cluster ion bombardment","authors":"Yukio Fujiwara","doi":"10.1116/6.0003500","DOIUrl":"https://doi.org/10.1116/6.0003500","url":null,"abstract":"Surface charging caused by the bombardment of samples with positive ion beams is a significant problem in material processing and surface analysis. The charging potential of an electrically isolated sample is commonly believed to increase with the acceleration voltage of a positive ion beam in the absence of charge compensation. Contrary to the common belief, however, this paper reports that the charging potential of an electrically isolated ionic liquid target decreases with increasing acceleration voltage of a positive cluster ion beam. A typical ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide (EMI-TFSA), was used as the target. It was placed on a metal plate that was electrically isolated from the ground, and its charging potential during cluster ion bombardment was measured with a high-impedance electrometer. For comparison, an electrically isolated metal plate was used. This study demonstrates that the charging potential varies significantly depending on cluster ion species and target materials. The charging potential of the metal plate increased monotonically with the irradiation time, whereas that of the ionic liquid target saturated at a lower voltage. The charging potential of the ionic liquid target decreased with increasing acceleration voltage of the ion beam even though the beam current increased. Larger cluster ions (m/z 502) caused less charge buildup than lighter cluster ions (m/z 111). The results obtained are explained by considering secondary ion emission from the ionic liquid target, which reduce the incoming net charge into the target, resulting in reduced surface charging.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":" 34","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140685053","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 high-density hydrogen plasma with a plasma density higher than 1010 cm−3 is produced by a radio-frequency magnetized capacitively coupled discharge using a hollow cathode, i.e., a cylindrical hole inside the powered electrode surrounded by eight cylindrical neodymium magnets. The magnetic field is calculated to discuss the electron magnetization, i.e., the Hall parameter and Larmor radius of electrons. It is found that for 3 Pa of hydrogen gas pressure the maximum of plasma density estimated from the ion saturation current measured by a Langmuir probe at the center of the hollow trench, which is surrounded by the magnets, is approximately 1.7 times higher than that without the magnets. The addition of magnets results in an expansion of the high-density plasma region inside the trench. The uniformity of the radial profile of the plasma density is better in the presence of the magnets than that without the magnets.
通过使用空心阴极的射频磁化电容耦合放电产生了等离子体密度高于 1010 cm-3 的高密度氢等离子体，空心阴极是指供电电极内的一个圆柱形孔，周围有八个圆柱形钕磁铁。通过计算磁场来讨论电子磁化，即电子的霍尔参数和拉莫尔半径。研究发现，在氢气压力为 3 Pa 的情况下，由磁体环绕的空心沟槽中心的朗缪尔探针测得的离子饱和电流估算出的等离子体密度最大值约为无磁体时的 1.7 倍。磁体的加入导致沟槽内高密度等离子体区域的扩大。在有磁体的情况下，等离子体密度径向分布的均匀性要好于没有磁体的情况。
{"title":"Production of a high-density hydrogen plasma in a capacitively coupled RF discharge with a hollow cathode enclosed by magnets","authors":"Y. Ohtsu, Takeshi Uchida, Ryohei Kuno, J. Schulze","doi":"10.1116/6.0003448","DOIUrl":"https://doi.org/10.1116/6.0003448","url":null,"abstract":"A high-density hydrogen plasma with a plasma density higher than 1010 cm−3 is produced by a radio-frequency magnetized capacitively coupled discharge using a hollow cathode, i.e., a cylindrical hole inside the powered electrode surrounded by eight cylindrical neodymium magnets. The magnetic field is calculated to discuss the electron magnetization, i.e., the Hall parameter and Larmor radius of electrons. It is found that for 3 Pa of hydrogen gas pressure the maximum of plasma density estimated from the ion saturation current measured by a Langmuir probe at the center of the hollow trench, which is surrounded by the magnets, is approximately 1.7 times higher than that without the magnets. The addition of magnets results in an expansion of the high-density plasma region inside the trench. The uniformity of the radial profile of the plasma density is better in the presence of the magnets than that without the magnets.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140686013","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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