A. Hiraiwa, K. Horikawa, Hiroshi Kawarada, M. Kado, K. Danno
The influence of Al2O3 atomic-layer deposition (ALD) temperature on the electric characteristics of Al/Al2O3/(2¯01) β-Ga2O3 capacitors was investigated focusing on the positive-bias instability (PBI) of the capacitors. The current in the capacitors increased with ALD temperature, mostly because of the reduced energy barrier height for the electron field emission from the substrate and less negative Al2O3 charge, as revealed by the analysis conducted assuming a space-charge-controlled field emission process. The PBI tests were conducted for cumulative voltage stressing times vastly ranging from 3 × 10−6 to 4 × 105 s. The capacitance–voltage (C–V) characteristics of the capacitors for an ALD temperature of 100 °C displayed negative shifts in the middle of voltage stressing, unlike those for the other ALD temperatures. The bias stability of the capacitors was found to be considerably improved by high-temperature (450 °C) ALD. Additionally, the C–V characteristic shifts caused by the voltage stressing were theoretically reproduced quite accurately, assuming a model proposed in this study. In the simulations, the trap distributions in the Al2O3 films were assumed to be uniform both spatially and energetically. Importantly, the experimental results for various stressing voltages were excellently fitted by the simulations that assumed the same trap distribution. The trap densities in the Al2O3 films thus estimated reduced from 1.2 × 1020 to 2.2 × 1019 cm−3 eV−1 for ALD temperatures of 100–450 °C. This reduction in the trap densities was a major cause of the bias stability enhancement for high-temperature ALD. Moreover, the trap density as a function of ALD temperature qualitatively agreed with the aforementioned Al2O3 charge generated by the current measurements. This agreement provides a strong basis for the validity of the PBI model proposed in this study.
{"title":"Influence of Al2O3 atomic-layer deposition temperature on positive-bias instability of metal/Al2O3/β-Ga2O3 capacitors","authors":"A. Hiraiwa, K. Horikawa, Hiroshi Kawarada, M. Kado, K. Danno","doi":"10.1116/6.0003186","DOIUrl":"https://doi.org/10.1116/6.0003186","url":null,"abstract":"The influence of Al2O3 atomic-layer deposition (ALD) temperature on the electric characteristics of Al/Al2O3/(2¯01) β-Ga2O3 capacitors was investigated focusing on the positive-bias instability (PBI) of the capacitors. The current in the capacitors increased with ALD temperature, mostly because of the reduced energy barrier height for the electron field emission from the substrate and less negative Al2O3 charge, as revealed by the analysis conducted assuming a space-charge-controlled field emission process. The PBI tests were conducted for cumulative voltage stressing times vastly ranging from 3 × 10−6 to 4 × 105 s. The capacitance–voltage (C–V) characteristics of the capacitors for an ALD temperature of 100 °C displayed negative shifts in the middle of voltage stressing, unlike those for the other ALD temperatures. The bias stability of the capacitors was found to be considerably improved by high-temperature (450 °C) ALD. Additionally, the C–V characteristic shifts caused by the voltage stressing were theoretically reproduced quite accurately, assuming a model proposed in this study. In the simulations, the trap distributions in the Al2O3 films were assumed to be uniform both spatially and energetically. Importantly, the experimental results for various stressing voltages were excellently fitted by the simulations that assumed the same trap distribution. The trap densities in the Al2O3 films thus estimated reduced from 1.2 × 1020 to 2.2 × 1019 cm−3 eV−1 for ALD temperatures of 100–450 °C. This reduction in the trap densities was a major cause of the bias stability enhancement for high-temperature ALD. Moreover, the trap density as a function of ALD temperature qualitatively agreed with the aforementioned Al2O3 charge generated by the current measurements. This agreement provides a strong basis for the validity of the PBI model proposed in this study.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"21 S10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139635014","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}
Volcano-structured field emitter arrays (FEAs) have achieved high-beam focusing and have been applied in electron beam lithography and image sensors. However, high current operation on the order of milliamperes is necessary for applications such as x-ray sources and traveling wave tubes. Thus, this study applied a TiN coating to a volcano-structured Si-FEA, which has a high melting point favorable for high-current operation. Transmission electron microscopy and x-ray photoelectron spectroscopy revealed that TiN was uniformly deposited on the Si tip by DC magnetron sputtering with the atomic ratio of Ti to N being 1:1. The TiN-coated volcano-structured FEA exhibited excellent electron emission property (7.7 mA/1027 tips) and an electron emission stability of >6 mA for 60 min in pulse operation. These results are expected to aid in the development of next-generation electron sources that can realize high-current operations under high-beam-focusing conditions.
火山结构场发射器阵列（FEA）实现了高光束聚焦，并已应用于电子束光刻和图像传感器。然而，在 X 射线源和行波管等应用中，需要毫安级的大电流运行。因此，本研究将 TiN 涂层应用于火山结构的 Si-FEA，其熔点高，有利于大电流操作。透射电子显微镜和 X 射线光电子能谱显示，TiN 是通过直流磁控溅射均匀沉积在硅尖端的，Ti 与 N 的原子比为 1:1。涂有 TiN 的火山结构 FEA 表现出优异的电子发射特性（7.7 mA/1027个尖端），在脉冲操作中，电子发射稳定性大于 6 mA，持续 60 分钟。这些结果有望帮助开发新一代电子源，实现高光束聚焦条件下的大电流运行。
{"title":"Electron emission properties of titanium nitride coated volcano-structured silicon emitters","authors":"H. Murata, K. Murakami, Masayoshi Nagao","doi":"10.1116/6.0003234","DOIUrl":"https://doi.org/10.1116/6.0003234","url":null,"abstract":"Volcano-structured field emitter arrays (FEAs) have achieved high-beam focusing and have been applied in electron beam lithography and image sensors. However, high current operation on the order of milliamperes is necessary for applications such as x-ray sources and traveling wave tubes. Thus, this study applied a TiN coating to a volcano-structured Si-FEA, which has a high melting point favorable for high-current operation. Transmission electron microscopy and x-ray photoelectron spectroscopy revealed that TiN was uniformly deposited on the Si tip by DC magnetron sputtering with the atomic ratio of Ti to N being 1:1. The TiN-coated volcano-structured FEA exhibited excellent electron emission property (7.7 mA/1027 tips) and an electron emission stability of >6 mA for 60 min in pulse operation. These results are expected to aid in the development of next-generation electron sources that can realize high-current operations under high-beam-focusing conditions.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"22 46","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139631485","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}
F. F. Ince, Mega Frost, D. Shima, Thomas J. Rotter, S. Addamane, C. Canedy, S. Tomasulo, C. Kim, W. Bewley, I. Vurgaftman, J. Meyer, Ganesh Balakrishnan
The epitaxial development and characterization of metamorphic “GaSb-on-silicon” buffers as substrates for antimonide devices is presented. The approach involves the growth of a spontaneously and fully relaxed GaSb metamorphic buffer in a primary epitaxial reactor, and use of the resulting “GaSb-on-silicon” wafer to grow subsequent layers in a secondary epitaxial reactor. The buffer growth involves four steps—silicon substrate preparation for oxide removal, nucleation of AlSb on silicon, growth of the GaSb buffer, and finally capping of the buffer to prevent oxidation. This approach on miscut silicon substrates leads to a buffer with negligible antiphase domain density. The growth of this buffer is based on inducing interfacial misfit dislocations between an AlSb nucleation layer and the underlying silicon substrate, which results in a fully relaxed GaSb buffer. A 1 μm thick GaSb layer buffer grown on silicon has ∼9.2 × 107dislocations/cm2. The complete lack of strain in the epitaxial structure allows subsequent growths to be accurately lattice matched, thus making the approach ideal for use as a substrate. We characterize the GaSb-on-silicon wafer using high-resolution x-ray diffraction and transmission electron microscopy. The concept’s feasibility is demonstrated by growing interband cascade light emitting devices on the GaSb-on-silicon wafer. The performance of the resulting LEDs on silicon approaches that of counterparts grown lattice matched on GaSb.
{"title":"Development of “GaSb-on-silicon” metamorphic substrates for optoelectronic device growth","authors":"F. F. Ince, Mega Frost, D. Shima, Thomas J. Rotter, S. Addamane, C. Canedy, S. Tomasulo, C. Kim, W. Bewley, I. Vurgaftman, J. Meyer, Ganesh Balakrishnan","doi":"10.1116/6.0003211","DOIUrl":"https://doi.org/10.1116/6.0003211","url":null,"abstract":"The epitaxial development and characterization of metamorphic “GaSb-on-silicon” buffers as substrates for antimonide devices is presented. The approach involves the growth of a spontaneously and fully relaxed GaSb metamorphic buffer in a primary epitaxial reactor, and use of the resulting “GaSb-on-silicon” wafer to grow subsequent layers in a secondary epitaxial reactor. The buffer growth involves four steps—silicon substrate preparation for oxide removal, nucleation of AlSb on silicon, growth of the GaSb buffer, and finally capping of the buffer to prevent oxidation. This approach on miscut silicon substrates leads to a buffer with negligible antiphase domain density. The growth of this buffer is based on inducing interfacial misfit dislocations between an AlSb nucleation layer and the underlying silicon substrate, which results in a fully relaxed GaSb buffer. A 1 μm thick GaSb layer buffer grown on silicon has ∼9.2 × 107dislocations/cm2. The complete lack of strain in the epitaxial structure allows subsequent growths to be accurately lattice matched, thus making the approach ideal for use as a substrate. We characterize the GaSb-on-silicon wafer using high-resolution x-ray diffraction and transmission electron microscopy. The concept’s feasibility is demonstrated by growing interband cascade light emitting devices on the GaSb-on-silicon wafer. The performance of the resulting LEDs on silicon approaches that of counterparts grown lattice matched on GaSb.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"15 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139631638","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}
Mohammad Istiaque Rahaman, G. Szakmany, A. O. Orlov, G. L. Snider
Charge sensing applications utilizing single electron transistors (SETs) as electrometers face challenges due to nearby background charge movements. In this study, we present an innovative fabrication method for creating suspended Al-AlOx-Al SETs positioned above a cavity. These suspended SETs exhibit significantly reduced flicker noise with 1fα noise spectral density when compared to their substrate-based counterparts. This noise reduction can be attributed to the elimination of the substrate beneath the SET island. Consequently, our fabricated suspended SETs are highly suitable for demanding charge sensing applications and provide a promising platform for in-depth investigations into the sources of charge noise in such devices.
由于附近的背景电荷运动，利用单电子晶体管（SET）作为电量计的电荷传感应用面临着挑战。在这项研究中，我们提出了一种创新的制造方法，用于制造位于空腔上方的悬浮式 Al-AlOx-Al SET。与基于基底的同类器件相比，这些悬浮 SET 的闪烁噪声（噪声谱密度为 1fα）明显降低。这种噪声降低可归因于 SET 岛下方消除了基底。因此，我们制造的悬浮 SET 非常适合要求苛刻的电荷传感应用，并为深入研究此类器件中的电荷噪声源提供了一个前景广阔的平台。
{"title":"New method of fabrication of suspended metallic single electron transistor (SET)","authors":"Mohammad Istiaque Rahaman, G. Szakmany, A. O. Orlov, G. L. Snider","doi":"10.1116/6.0003025","DOIUrl":"https://doi.org/10.1116/6.0003025","url":null,"abstract":"Charge sensing applications utilizing single electron transistors (SETs) as electrometers face challenges due to nearby background charge movements. In this study, we present an innovative fabrication method for creating suspended Al-AlOx-Al SETs positioned above a cavity. These suspended SETs exhibit significantly reduced flicker noise with 1fα noise spectral density when compared to their substrate-based counterparts. This noise reduction can be attributed to the elimination of the substrate beneath the SET island. Consequently, our fabricated suspended SETs are highly suitable for demanding charge sensing applications and provide a promising platform for in-depth investigations into the sources of charge noise in such devices.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"21 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139395893","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 pumping performance of a range of Ti, V, Zr, and Hf alloy nonevaporable getter (NEG) coatings of order 5 μm thickness and with different modular structures has been investigated. For equal atomic percent Ti–Zr–V–Hf quaternary alloys, dual (columnar layer on the dense layer) coatings gave higher sticking probabilities than columnar and dense morphologies. The same alloy provided the highest sticking probability, followed by the Ti–Zr–V tertiary alloy, and then singular Zr. For a 24 h activation time, single element Zr coatings were shown to require an activation temperature of 300 vs 250 °C for the other alloys. H2 and N2 sticking probabilities increased by a factor of 100 and N2 terminal capacities by a factor of 1000, in the range 150–300 °C. For the dual coated Ti–Zr–V–Hf quaternary alloy at an activation temperature of 140 °C, H2 sticking probabilities increased by a factor of 2 when the activation time increased from 1 to 7 days and that of N2 increased by a factor of 6. The factor of 100 increase in measured sticking probability at LN2 temperature, compared to room temperature, to a value of 0.5 for H2, is transient in nature. Further investigations into this behavior are planned.
{"title":"Evaluation of the pumping performance of combinations of Ti–Zr–V–Hf alloy nonevaporable getter coatings with different morphologies, activation protocols controlled at cryogenic temperatures","authors":"Paul Smith, Sam Lodge, Andrew Chew","doi":"10.1116/6.0003152","DOIUrl":"https://doi.org/10.1116/6.0003152","url":null,"abstract":"The pumping performance of a range of Ti, V, Zr, and Hf alloy nonevaporable getter (NEG) coatings of order 5 μm thickness and with different modular structures has been investigated. For equal atomic percent Ti–Zr–V–Hf quaternary alloys, dual (columnar layer on the dense layer) coatings gave higher sticking probabilities than columnar and dense morphologies. The same alloy provided the highest sticking probability, followed by the Ti–Zr–V tertiary alloy, and then singular Zr. For a 24 h activation time, single element Zr coatings were shown to require an activation temperature of 300 vs 250 °C for the other alloys. H2 and N2 sticking probabilities increased by a factor of 100 and N2 terminal capacities by a factor of 1000, in the range 150–300 °C. For the dual coated Ti–Zr–V–Hf quaternary alloy at an activation temperature of 140 °C, H2 sticking probabilities increased by a factor of 2 when the activation time increased from 1 to 7 days and that of N2 increased by a factor of 6. The factor of 100 increase in measured sticking probability at LN2 temperature, compared to room temperature, to a value of 0.5 for H2, is transient in nature. Further investigations into this behavior are planned.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139637754","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}
Ionic liquid ion sources are expected to be used in a wide range of applications such as space electric propulsion and focused ion beam micromachining. It is known that the backstreaming of secondary charged species generated by ion beam impacts can cause unexpected temperature rise and chemical changes in ionic liquids. This paper reports on results of heating experiments using a sharp needle emitter wetted with an ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide, at temperatures in a range from room temperature to 120 °C. Current measurements show that positive and negative electrospray currents from the heated emitter increased as the temperature increased. Time-of-flight (TOF) mass spectrometric measurements reveal that the beam composition changed significantly with increasing temperature, indicating that charged droplets as well as ions were emitted from the heated emitter. The TOF data show that a significant fraction of the current is due to droplets at higher temperatures. On the basis of the results obtained, the size and charge of the emitted droplets are discussed. The beam is roughly estimated to contain charged droplets with a diameter of around 20 nm at 120 °C.
{"title":"Temperature effects on electrospray current from an externally wetted EMI-Im ionic liquid ion source","authors":"Y. Fujiwara","doi":"10.1116/6.0003088","DOIUrl":"https://doi.org/10.1116/6.0003088","url":null,"abstract":"Ionic liquid ion sources are expected to be used in a wide range of applications such as space electric propulsion and focused ion beam micromachining. It is known that the backstreaming of secondary charged species generated by ion beam impacts can cause unexpected temperature rise and chemical changes in ionic liquids. This paper reports on results of heating experiments using a sharp needle emitter wetted with an ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethanesulfonyl)amide, at temperatures in a range from room temperature to 120 °C. Current measurements show that positive and negative electrospray currents from the heated emitter increased as the temperature increased. Time-of-flight (TOF) mass spectrometric measurements reveal that the beam composition changed significantly with increasing temperature, indicating that charged droplets as well as ions were emitted from the heated emitter. The TOF data show that a significant fraction of the current is due to droplets at higher temperatures. On the basis of the results obtained, the size and charge of the emitted droplets are discussed. The beam is roughly estimated to contain charged droplets with a diameter of around 20 nm at 120 °C.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"53 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139015124","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}
Copper oxides are nontoxic semiconductors with good stability and abundance of raw materials. In each of the applications, it is advisable to look for a method to improve the properties of thin films of these materials, such as electrical conductivity or light absorption. In this work, thin films were prepared by reactive magnetron sputtering and doped with chromium using the ion implantation method. The samples were implanted with chromium ions with energy of 10–25 keV and various doses ranging from 1 × 1014 to 1 × 1017 cm−2. Their optical properties were investigated using spectroscopic ellipsometry and spectrophotometry with absorption measurement. Multilayer models of the dielectric function of materials were established based on oscillator equations to obtain the values of optical parameters such as refractive index and extinction coefficient. Measurements using the ellipsometer allowed us to examine the homogeneity of the samples after deposition, as well as after the implantation process, by measuring 4 × 4 mm2 maps of the pseudorefractive index of the samples. Ion implantation affects the optical properties of copper oxides, and these changes are expected to come from the top thickness of the implanted films, i.e., the range in which the implanted ions penetrate. Using multilayer models to analyze the results of spectroscopic ellipsometry, it was possible to estimate the thickness of the layer that has the greatest impact on the optical properties of the oxides.
{"title":"Optical properties of copper oxide thin films implanted with chromium ions","authors":"K. Ungeheuer, K. W. Marszalek","doi":"10.1116/6.0003135","DOIUrl":"https://doi.org/10.1116/6.0003135","url":null,"abstract":"Copper oxides are nontoxic semiconductors with good stability and abundance of raw materials. In each of the applications, it is advisable to look for a method to improve the properties of thin films of these materials, such as electrical conductivity or light absorption. In this work, thin films were prepared by reactive magnetron sputtering and doped with chromium using the ion implantation method. The samples were implanted with chromium ions with energy of 10–25 keV and various doses ranging from 1 × 1014 to 1 × 1017 cm−2. Their optical properties were investigated using spectroscopic ellipsometry and spectrophotometry with absorption measurement. Multilayer models of the dielectric function of materials were established based on oscillator equations to obtain the values of optical parameters such as refractive index and extinction coefficient. Measurements using the ellipsometer allowed us to examine the homogeneity of the samples after deposition, as well as after the implantation process, by measuring 4 × 4 mm2 maps of the pseudorefractive index of the samples. Ion implantation affects the optical properties of copper oxides, and these changes are expected to come from the top thickness of the implanted films, i.e., the range in which the implanted ions penetrate. Using multilayer models to analyze the results of spectroscopic ellipsometry, it was possible to estimate the thickness of the layer that has the greatest impact on the optical properties of the oxides.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"49 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139025206","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 this paper, the electron collection efficiency of dynodes in different electron multiplier (EM) structures is analyzed using Computer Simulation Technology. Three main factors that lead to low efficiency in electronic collection have been identified as crossing, trapped, and blocked electrons. The proportions of these three types of electrons are investigated to illustrate the characteristics of EMs with different structures. It is observed that the optimized 3D structure outperforms all 2D structures, and the reasons for this improvement are also discussed. The spiral EM is designed to achieve an average collection efficiency of 98.9% at the optimal parameters. By adopting the proposed structure, not only the size of the EM can be reduced, but also the gain of the EM can be significantly improved. Consequently, this will allow for a reduction in the operating voltage of the EM and prolong its lifetime.
本文利用计算机仿真技术分析了不同电子倍增器（EM）结构中 dynodes 的电子收集效率。导致电子收集效率低的三个主要因素被确定为交叉电子、陷落电子和阻塞电子。研究了这三类电子的比例，以说明不同结构的 EM 的特点。据观察，优化后的三维结构优于所有二维结构，并讨论了这种改进的原因。在最佳参数下，螺旋 EM 的平均收集效率达到 98.9%。通过采用所建议的结构，不仅可以减小电磁元件的尺寸，还能显著提高电磁元件的增益。因此，这可以降低电磁炉的工作电压，延长其使用寿命。
{"title":"3D structure of box-and-grid electron multiplier with higher electron collection efficiency","authors":"Zhangcong Xia, Yunrong Wang, Youwei Peng, Jie Li, Wenbo Hu, Xin Zhong, Shengli Wu","doi":"10.1116/6.0003162","DOIUrl":"https://doi.org/10.1116/6.0003162","url":null,"abstract":"In this paper, the electron collection efficiency of dynodes in different electron multiplier (EM) structures is analyzed using Computer Simulation Technology. Three main factors that lead to low efficiency in electronic collection have been identified as crossing, trapped, and blocked electrons. The proportions of these three types of electrons are investigated to illustrate the characteristics of EMs with different structures. It is observed that the optimized 3D structure outperforms all 2D structures, and the reasons for this improvement are also discussed. The spiral EM is designed to achieve an average collection efficiency of 98.9% at the optimal parameters. By adopting the proposed structure, not only the size of the EM can be reduced, but also the gain of the EM can be significantly improved. Consequently, this will allow for a reduction in the operating voltage of the EM and prolong its lifetime.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"15 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139023604","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}
An updated version of an Invar-based dual Fabry–Perot cavity refractometer utilizing the gas modulation methodology has been characterized with regard to its ability to assess gas pressure in the low pressure regime, defined as the regime in which the instrumentation is mainly limited by the constant term a in the [(a)2+(b×P)2]1/2 expression for the uncertainty. It is first concluded that this ability is predominantly limited by three entities, viz., the empty cavity repeatability, the residual gas pressures in the evacuated (measurement) cavity, and the contamination of the gas residing in the measurement cavity that originates from leaks and outgassing. We then present and utilize methods to separately estimate the uncertainty of the updated refractometer from these entities. It was found that, when utilizing gas modulation cycles of 100 s and when addressing nitrogen, the system can assess pressure in the low pressure regime with an expanded uncertainty (k=2) of 0.75 mPa, mainly limited by the empty cavity repeatability and outgassing of hydrogen. This is more than 1 order of magnitude below the previously assessed low pressure performance of the instrumentation.
{"title":"An Invar-based dual Fabry–Perot cavity refractometer for assessment of pressure with a pressure independent uncertainty in the sub-mPa region","authors":"I. Silander, J. Zakrisson, M. Zelan, O. Axner","doi":"10.1116/6.0003149","DOIUrl":"https://doi.org/10.1116/6.0003149","url":null,"abstract":"An updated version of an Invar-based dual Fabry–Perot cavity refractometer utilizing the gas modulation methodology has been characterized with regard to its ability to assess gas pressure in the low pressure regime, defined as the regime in which the instrumentation is mainly limited by the constant term a in the [(a)2+(b×P)2]1/2 expression for the uncertainty. It is first concluded that this ability is predominantly limited by three entities, viz., the empty cavity repeatability, the residual gas pressures in the evacuated (measurement) cavity, and the contamination of the gas residing in the measurement cavity that originates from leaks and outgassing. We then present and utilize methods to separately estimate the uncertainty of the updated refractometer from these entities. It was found that, when utilizing gas modulation cycles of 100 s and when addressing nitrogen, the system can assess pressure in the low pressure regime with an expanded uncertainty (k=2) of 0.75 mPa, mainly limited by the empty cavity repeatability and outgassing of hydrogen. This is more than 1 order of magnitude below the previously assessed low pressure performance of the instrumentation.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"33 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139014604","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}
{"title":"Preface for the Special Topic Collection Honoring Dr. Gary McGuire’s Research and Leadership as Editor of the Journal of Vacuum Science & Technology for Three Decades","authors":"O. Shenderova, Susan Burkett","doi":"10.1116/6.0003134","DOIUrl":"https://doi.org/10.1116/6.0003134","url":null,"abstract":"","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"143 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138622293","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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