Pub Date : 2024-03-01Epub Date: 2024-02-05DOI: 10.1116/6.0003249
Shin Muramoto, Daniel J Graham, David G Castner
Organic thin films are of great interest due to their intriguing interfacial and functional properties, especially for device applications such as thin-film transistors and sensors. As their thickness approaches single nanometer thickness, characterization and interpretation of the extracted data become increasingly complex. In this study, plasma polymerization is used to construct ultrathin films that range in thickness from 1 to 20 nm, and time-of-flight secondary ion mass spectrometry coupled with principal component analysis is used to investigate the effects of film thickness on the resulting spectra. We demonstrate that for these cross-linked plasma polymers, at these thicknesses, the observed trends are different from those obtained from thicker films with lower degrees of cross-linking: contributions from ambient carbon contamination start to dominate the mass spectrum; cluster-induced nonlinear enhancement in secondary ion yield is no longer observed; extent of fragmentation is higher due to confinement of the primary ion energy; and the size of the primary ion source also affects fragmentation (e.g., Bi1 versus Bi5). These differences illustrate that care must be taken in choosing the correct primary ion source as well as in interpreting the data.
{"title":"ToF-SIMS analysis of ultrathin films and their fragmentation patterns.","authors":"Shin Muramoto, Daniel J Graham, David G Castner","doi":"10.1116/6.0003249","DOIUrl":"10.1116/6.0003249","url":null,"abstract":"<p><p>Organic thin films are of great interest due to their intriguing interfacial and functional properties, especially for device applications such as thin-film transistors and sensors. As their thickness approaches single nanometer thickness, characterization and interpretation of the extracted data become increasingly complex. In this study, plasma polymerization is used to construct ultrathin films that range in thickness from 1 to 20 nm, and time-of-flight secondary ion mass spectrometry coupled with principal component analysis is used to investigate the effects of film thickness on the resulting spectra. We demonstrate that for these cross-linked plasma polymers, at these thicknesses, the observed trends are different from those obtained from thicker films with lower degrees of cross-linking: contributions from ambient carbon contamination start to dominate the mass spectrum; cluster-induced nonlinear enhancement in secondary ion yield is no longer observed; extent of fragmentation is higher due to confinement of the primary ion energy; and the size of the primary ion source also affects fragmentation (e.g., Bi<sub>1</sub> versus Bi<sub>5</sub>). These differences illustrate that care must be taken in choosing the correct primary ion source as well as in interpreting the data.</p>","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"42 2","pages":"023416"},"PeriodicalIF":2.9,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10846908/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139702854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LiGa5O8 in the spinel type structure is investigated as a potential ultra-wideband-gap semiconductor. The band structure is determined using the quasiparticle self-consistent GW method, and the optical properties are calculated at the Bethe Salpeter Equation level including electron-hole interaction effects. The optical gap including exciton effects and an estimate of the zero-point motion electron phonon coupling renormalizations is estimated to be about 5.2±0.1 eV with an exciton binding energy of about 0.4 eV. Si doping as potential n-type dopant is investigated and found to be a promising shallow donor.
{"title":"Spinel LiGa5O8 prospects as ultra-wideband-gap semiconductor: Band structure, optical properties, and doping","authors":"Walter R. L. Lambrecht","doi":"10.1116/6.0003117","DOIUrl":"https://doi.org/10.1116/6.0003117","url":null,"abstract":"LiGa5O8 in the spinel type structure is investigated as a potential ultra-wideband-gap semiconductor. The band structure is determined using the quasiparticle self-consistent GW method, and the optical properties are calculated at the Bethe Salpeter Equation level including electron-hole interaction effects. The optical gap including exciton effects and an estimate of the zero-point motion electron phonon coupling renormalizations is estimated to be about 5.2±0.1 eV with an exciton binding energy of about 0.4 eV. Si doping as potential n-type dopant is investigated and found to be a promising shallow donor.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"17 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Taylor G. Smith, Ali M. Ali, Jean-François de Marneffe, Jane P. Chang
Nickel (Ni) and its alloys are important multifunctional materials for the fabrication of integrated circuits, as either the absorber for the extreme ultraviolet lithography masks and/or interconnect metals at the nanometer scale. However, these applications require that Ni to be patterned controllably, selectively, and anisotropically—requirements that can only be met with a plasma based atomic layer etch (ALE) process. In this work, a plasma-thermal ALE approach is developed to pattern Ni, utilizing a nitrogen plasma to form NixN at the surface, formic acid (FA) vapor to selectively remove the NixN layer, and a low-energy Ar+ sputter process to remove carbon residue left by the FA prior to the subsequent nitridation step. This three step ALE process was shown effective to etch Ni with a rate of 1.3 ± 0.17 nm/cycle while maintaining surface smoothness.
镍（Ni）及其合金是制造集成电路的重要多功能材料，可用作极紫外线光刻掩模的吸收剂和/或纳米尺度的互连金属。然而，这些应用要求对镍进行可控、选择性和各向异性的图案化，而只有基于等离子体的原子层蚀刻（ALE）工艺才能满足这些要求。在这项工作中，开发了一种等离子体-热原子层蚀刻 (ALE) 方法，利用氮等离子体在表面形成 NixN，利用甲酸 (FA) 蒸汽选择性地去除 NixN 层，并利用低能 Ar+ 溅射工艺去除 FA 在随后的氮化步骤之前留下的碳残留物，从而对镍进行图案化。结果表明，这种三步 ALE 工艺能有效地蚀刻镍，蚀刻速率为 1.3 ± 0.17 nm/周期，同时保持表面光滑。
{"title":"Plasma nitridation for atomic layer etching of Ni","authors":"Taylor G. Smith, Ali M. Ali, Jean-François de Marneffe, Jane P. Chang","doi":"10.1116/6.0003263","DOIUrl":"https://doi.org/10.1116/6.0003263","url":null,"abstract":"Nickel (Ni) and its alloys are important multifunctional materials for the fabrication of integrated circuits, as either the absorber for the extreme ultraviolet lithography masks and/or interconnect metals at the nanometer scale. However, these applications require that Ni to be patterned controllably, selectively, and anisotropically—requirements that can only be met with a plasma based atomic layer etch (ALE) process. In this work, a plasma-thermal ALE approach is developed to pattern Ni, utilizing a nitrogen plasma to form NixN at the surface, formic acid (FA) vapor to selectively remove the NixN layer, and a low-energy Ar+ sputter process to remove carbon residue left by the FA prior to the subsequent nitridation step. This three step ALE process was shown effective to etch Ni with a rate of 1.3 ± 0.17 nm/cycle while maintaining surface smoothness.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"273 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate intermittent plasticity in nanopillars of nanocrystalline molybdenum based on in situ transmission electron microscopy observations. By correlating electron imaging results with the measured nanopillar mechanical response, we demonstrate that the intermittent plasticity in nanocrystalline molybdenum is largely caused by dislocation avalanches. Electron imaging further reveals three types of dislocation avalanches, from intragranular to transgranular to cross-granular avalanches. The measured strain bursts resulted from avalanches have similar magnitudes to those reported for the molybdenum single-crystal pillars, while the corresponding flow stress in nanocrystalline molybdenum is greatly enhanced by the small grain size. Statistical analysis also shows that the avalanches behavior has similar characteristic as single crystals in the mean field theory model. Together, our findings here provide critical insights into the deformation mechanisms in a nanostructured body-centered-cubic metal.
{"title":"Dislocation avalanches in nanostructured molybdenum nanopillars","authors":"Haw-Wen Hsiao, Jia-Hong Huang, Jian-Min Zuo","doi":"10.1116/6.0003254","DOIUrl":"https://doi.org/10.1116/6.0003254","url":null,"abstract":"We investigate intermittent plasticity in nanopillars of nanocrystalline molybdenum based on in situ transmission electron microscopy observations. By correlating electron imaging results with the measured nanopillar mechanical response, we demonstrate that the intermittent plasticity in nanocrystalline molybdenum is largely caused by dislocation avalanches. Electron imaging further reveals three types of dislocation avalanches, from intragranular to transgranular to cross-granular avalanches. The measured strain bursts resulted from avalanches have similar magnitudes to those reported for the molybdenum single-crystal pillars, while the corresponding flow stress in nanocrystalline molybdenum is greatly enhanced by the small grain size. Statistical analysis also shows that the avalanches behavior has similar characteristic as single crystals in the mean field theory model. Together, our findings here provide critical insights into the deformation mechanisms in a nanostructured body-centered-cubic metal.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"39 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the lack of research on the microscopic evolution process and the formation of step growth patterns for SiC crystals, it is of great importance to deepen the understanding of the epitaxial growth of a SiC vicinal surface from a microscopic point of view. In this study, a three-dimensional lattice kinetic Monte Carlo algorithm was used to study the step flow growth characteristics of SiC crystals. The microscopic evolution of the step flow growth patterns for SiC vicinal surfaces was shown. C and Si were treated as the basic particles, and the net deposition and diffusion of atoms were considered in this model. The periodic boundary conditions were applied along the step edge and the helical boundary conditions were applied in the direction perpendicular to the step. The surface morphology evolution of SiC crystals grown on step substrates was simulated at different growth temperatures, partial deposition fluxes, and terrace widths. The results indicated that the growth patterns of the SiC vicinal surface could be transformed from a step flow growth to a nucleation growth pattern by decreasing the growth temperature, increasing the deposition flux, and increasing the terrace width.
由于缺乏对 SiC 晶体微观演化过程和阶梯生长模式形成的研究，因此从微观角度加深对 SiC 晶面外延生长的理解具有重要意义。本研究采用三维晶格动力学蒙特卡洛算法研究了 SiC 晶体的阶梯流生长特性。研究显示了 SiC 晶面阶梯流生长模式的微观演化过程。该模型将 C 和 Si 视为基本粒子，并考虑了原子的净沉积和扩散。沿着阶梯边缘应用了周期性边界条件，在垂直于阶梯的方向应用了螺旋边界条件。在不同的生长温度、部分沉积通量和台阶宽度下，模拟了在台阶基底上生长的碳化硅晶体的表面形貌演变。结果表明，通过降低生长温度、增加沉积通量和增大台阶宽度，SiC 的临界表面生长模式可从台阶流生长转变为成核生长模式。
{"title":"Kinetic Monte Carlo study on the effect of growth conditions on the epitaxial growth of 3C–SiC (0001) vicinal surface","authors":"Xuejiang Chen, Xinyao Zhang, Wensen Ai","doi":"10.1116/6.0003144","DOIUrl":"https://doi.org/10.1116/6.0003144","url":null,"abstract":"Due to the lack of research on the microscopic evolution process and the formation of step growth patterns for SiC crystals, it is of great importance to deepen the understanding of the epitaxial growth of a SiC vicinal surface from a microscopic point of view. In this study, a three-dimensional lattice kinetic Monte Carlo algorithm was used to study the step flow growth characteristics of SiC crystals. The microscopic evolution of the step flow growth patterns for SiC vicinal surfaces was shown. C and Si were treated as the basic particles, and the net deposition and diffusion of atoms were considered in this model. The periodic boundary conditions were applied along the step edge and the helical boundary conditions were applied in the direction perpendicular to the step. The surface morphology evolution of SiC crystals grown on step substrates was simulated at different growth temperatures, partial deposition fluxes, and terrace widths. The results indicated that the growth patterns of the SiC vicinal surface could be transformed from a step flow growth to a nucleation growth pattern by decreasing the growth temperature, increasing the deposition flux, and increasing the terrace width.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"25 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Cristea, A. I. Scărlătescu, G. Bulai, D. Martínez-Martínez, C. I. da Silva Oliveira, G. Yan, L. Cunha
Reactive magnetron sputtering was used to deposit Ti:Zr-O-N thin films, by using a single Zr target, with Ti ribbons placed on the erosion track of the Zr sputtering target. Zr-O-N thin films have been also deposited in the same chamber to be used as reference films. The number of Ti ribbons, the applied sputtering current, and the reactive gas flow were the variable parameters. The films were analyzed in terms of structural development and mechanical properties (instrumented indentation, adhesion scratch testing, and wear analysis). The films are either amorphous or composed of a mixture of crystalline phases based on zirconium and titanium oxides or nitrides. Hardness values are situated between ∼10 and 11 GPa for the reference films (deposited without Ti) and up to ∼22 GPa for one of the Ti:Zr-O-N films. The films deposited without Ti behave slightly better in terms of adhesion to the substrate in comparison to the remaining samples in relation to the occurrence of first cracks (Lc1, critical load 1) and for first delamination (Lc2, critical load 2), a phenomenon probably related to the lower hardness of these films, which can accommodate the plastic deformation caused by the diamond indenter, prior to the occurrence of delamination. Adhesion to the substrate is a critical characteristic during wear tests since some of the coatings exhibit severe delamination.
{"title":"Hardness, adhesion, and wear behavior of magnetron cosputtered Ti:Zr-O-N thin films","authors":"D. Cristea, A. I. Scărlătescu, G. Bulai, D. Martínez-Martínez, C. I. da Silva Oliveira, G. Yan, L. Cunha","doi":"10.1116/6.0003267","DOIUrl":"https://doi.org/10.1116/6.0003267","url":null,"abstract":"Reactive magnetron sputtering was used to deposit Ti:Zr-O-N thin films, by using a single Zr target, with Ti ribbons placed on the erosion track of the Zr sputtering target. Zr-O-N thin films have been also deposited in the same chamber to be used as reference films. The number of Ti ribbons, the applied sputtering current, and the reactive gas flow were the variable parameters. The films were analyzed in terms of structural development and mechanical properties (instrumented indentation, adhesion scratch testing, and wear analysis). The films are either amorphous or composed of a mixture of crystalline phases based on zirconium and titanium oxides or nitrides. Hardness values are situated between ∼10 and 11 GPa for the reference films (deposited without Ti) and up to ∼22 GPa for one of the Ti:Zr-O-N films. The films deposited without Ti behave slightly better in terms of adhesion to the substrate in comparison to the remaining samples in relation to the occurrence of first cracks (Lc1, critical load 1) and for first delamination (Lc2, critical load 2), a phenomenon probably related to the lower hardness of these films, which can accommodate the plastic deformation caused by the diamond indenter, prior to the occurrence of delamination. Adhesion to the substrate is a critical characteristic during wear tests since some of the coatings exhibit severe delamination.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"11 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work presents the atomic layer etching (ALE) process for sputtered indium tin oxide (ITO) thin films using thermal surface modification with BCl3 and modified surface removal by low ion energy Ar plasma. In this approach, an elevated temperature is required for high synergy ALE due to the low volatility of indium chlorides, and 150°C is proved to be suitable. An etch per cycle (EPC) of 1.1 Å and ALE synergy of 82% was achieved. Both surface modification and modified surface removal steps exhibited self-limited EPC. The ALE process was developed in a conventional reactive ion etching tool and retains the thin film absolute uniformity on the wafer. ITO was photolithographically patterned on whole wafers using photoresist as an etch mask for the ALE, and clear smoothing of the unmasked areas is observed, which is a characteristic of an ideal ALE process. This confirms that the developed ALE process can be utilized to pattern ITO using conventional photolithography. The demonstrated ITO ALE can be used to fabricate, for example, thin channel or recessed channel transistors, with self-smoothened channels for reduced surface scattering.
这项工作介绍了利用 BCl3 热表面改性和低离子能量 Ar 等离子体改性表面去除溅射铟锡氧化物（ITO）薄膜的原子层蚀刻（ALE）工艺。在这种方法中，由于氯氧化铟的挥发性较低，因此需要较高的温度来实现高协同 ALE，事实证明 150°C 是合适的温度。每周期蚀刻 (EPC) 为 1.1 Å，ALE 协同作用达到 82%。表面改性和改性表面去除步骤都表现出自限制 EPC。ALE 工艺是在传统的反应离子蚀刻工具中开发的，能在晶片上保持薄膜的绝对均匀性。使用光刻胶作为 ALE 的蚀刻掩模，在整个晶片上对 ITO 进行光刻图案化，观察到未掩模区域明显平滑，这是理想 ALE 工艺的特征。这证实了所开发的 ALE 工艺可用于使用传统光刻技术绘制 ITO 图形。所展示的 ITO ALE 可用于制造薄沟道或凹沟道晶体管等，其沟道具有自平滑功能，可减少表面散射。
{"title":"Atomic layer etching of indium tin oxide","authors":"Christoffer Kauppinen","doi":"10.1116/6.0003170","DOIUrl":"https://doi.org/10.1116/6.0003170","url":null,"abstract":"This work presents the atomic layer etching (ALE) process for sputtered indium tin oxide (ITO) thin films using thermal surface modification with BCl3 and modified surface removal by low ion energy Ar plasma. In this approach, an elevated temperature is required for high synergy ALE due to the low volatility of indium chlorides, and 150°C is proved to be suitable. An etch per cycle (EPC) of 1.1 Å and ALE synergy of 82% was achieved. Both surface modification and modified surface removal steps exhibited self-limited EPC. The ALE process was developed in a conventional reactive ion etching tool and retains the thin film absolute uniformity on the wafer. ITO was photolithographically patterned on whole wafers using photoresist as an etch mask for the ALE, and clear smoothing of the unmasked areas is observed, which is a characteristic of an ideal ALE process. This confirms that the developed ALE process can be utilized to pattern ITO using conventional photolithography. The demonstrated ITO ALE can be used to fabricate, for example, thin channel or recessed channel transistors, with self-smoothened channels for reduced surface scattering.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"63 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lars Freter, Liverios Lymperakis, Michael Schnedler, Holger Eisele, Lei Jin, Jianxun Liu, Qian Sun, Rafal E. Dunin-Borkowski, Philipp Ebert
Growth on nonpolar group III-nitride semiconductor surfaces has been suggested to be a remedy for avoiding detrimental polarization effects. However, the presence of intrinsic surface states within the fundamental bandgap at nonpolar surfaces leads to a Fermi-level pinning during growth, affecting the incorporation of dopants and impurities. This is further complicated by the use of ternary, e.g., AlxGa1−xN layers in device structures. In order to quantify the Fermi-level pinning on ternary group III nitride nonpolar growth surface, the energy position of the group III-derived empty dangling bond surface state at nonpolar AlxGa1−xN(101¯0) surfaces is determined as a function of the Al concentration using cross-sectional scanning tunneling microscopy and spectroscopy. The measurements show that the minimum energy of the empty dangling bond state shifts linearly toward midgap for increasing Al concentration with a slope of ≈5 meV/%. These experimental findings are supported by complementary density functional theory calculations.
有人认为，在非极性 III 族氮化物半导体表面生长是避免有害极化效应的一种补救方法。然而，由于非极性表面存在基带隙内的本征表面态，因此在生长过程中会出现费米级钉扎现象，从而影响掺杂剂和杂质的掺入。在器件结构中使用三元层（如 AlxGa1-xN 层）会使情况更加复杂。为了量化三元组 III 族氮化物非极性生长表面的费米级钉扎现象，利用横截面扫描隧道显微镜和光谱测定了非极性 AlxGa1-xN(101¯0)表面 III 族衍生空悬空键表面态的能量位置与铝浓度的函数关系。测量结果表明，随着铝浓度的增加，空悬空键态的最小能量线性地向中隙移动，斜率≈5 meV/%。这些实验结果得到了补充密度泛函理论计算的支持。
{"title":"Composition dependence of intrinsic surface states and Fermi-level pinning at ternary AlxGa1−xN m-plane surfaces","authors":"Lars Freter, Liverios Lymperakis, Michael Schnedler, Holger Eisele, Lei Jin, Jianxun Liu, Qian Sun, Rafal E. Dunin-Borkowski, Philipp Ebert","doi":"10.1116/6.0003225","DOIUrl":"https://doi.org/10.1116/6.0003225","url":null,"abstract":"Growth on nonpolar group III-nitride semiconductor surfaces has been suggested to be a remedy for avoiding detrimental polarization effects. However, the presence of intrinsic surface states within the fundamental bandgap at nonpolar surfaces leads to a Fermi-level pinning during growth, affecting the incorporation of dopants and impurities. This is further complicated by the use of ternary, e.g., AlxGa1−xN layers in device structures. In order to quantify the Fermi-level pinning on ternary group III nitride nonpolar growth surface, the energy position of the group III-derived empty dangling bond surface state at nonpolar AlxGa1−xN(101¯0) surfaces is determined as a function of the Al concentration using cross-sectional scanning tunneling microscopy and spectroscopy. The measurements show that the minimum energy of the empty dangling bond state shifts linearly toward midgap for increasing Al concentration with a slope of ≈5 meV/%. These experimental findings are supported by complementary density functional theory calculations.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"54 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There are few reported cases in which the spatial distribution of spectral emission coefficients of plasmas from tomographic optical emission spectroscopy measurements is analyzed based on a collisional-radiative model to diagnose the spatial distribution electron temperature of Te and density Ne. This study aimed at in situ diagnosis of process plasma. The spectral radiance of 18 lines-of-sight was measured simultaneously in argon inductively coupled plasma. The spatial distribution of the excited level number density distribution was calculated from the spatial distribution of spectral emission coefficients obtained from spectral tomography calculations. The three-dimensional distribution of Te and Ne was analyzed using a collisional-radiative model from the obtained spatial distribution of the excited levels number density. The effects of power and pressure on the dependence of the spatial distribution of Te and Ne were discussed. Furthermore, data processing methods for spectral tomographic measurements with coarse wavelength resolution were also discussed.
根据碰撞辐射模型分析断层扫描光学发射光谱测量得出的等离子体光谱发射系数的空间分布，以诊断Te的电子温度和Ne的密度的空间分布，这种方法鲜有报道。这项研究旨在对过程等离子体进行现场诊断。在氩电感耦合等离子体中同时测量了 18 条视线的光谱辐射率。通过光谱层析计算获得的光谱发射系数的空间分布，计算出激发级数密度分布的空间分布。根据获得的激发水平数密度空间分布，利用碰撞辐射模型分析了 Te 和 Ne 的三维分布。讨论了功率和压力对 Te 和 Ne 空间分布依赖性的影响。此外，还讨论了粗波长分辨率光谱断层测量的数据处理方法。
{"title":"Spatial distribution diagnosis of electron temperature and density of argon inductively coupled plasma by tomographic optical emission spectroscopic measurement and collisional-radiative model","authors":"Yuya Yamashita, Kenta Doi, Tetsuji Kiyota, Kenta Ishi, Shuhei Watanabe, Wataru Kikuchi, Atsushi Nezu, Hiroshi Akatsuka","doi":"10.1116/6.0003209","DOIUrl":"https://doi.org/10.1116/6.0003209","url":null,"abstract":"There are few reported cases in which the spatial distribution of spectral emission coefficients of plasmas from tomographic optical emission spectroscopy measurements is analyzed based on a collisional-radiative model to diagnose the spatial distribution electron temperature of Te and density Ne. This study aimed at in situ diagnosis of process plasma. The spectral radiance of 18 lines-of-sight was measured simultaneously in argon inductively coupled plasma. The spatial distribution of the excited level number density distribution was calculated from the spatial distribution of spectral emission coefficients obtained from spectral tomography calculations. The three-dimensional distribution of Te and Ne was analyzed using a collisional-radiative model from the obtained spatial distribution of the excited levels number density. The effects of power and pressure on the dependence of the spatial distribution of Te and Ne were discussed. Furthermore, data processing methods for spectral tomographic measurements with coarse wavelength resolution were also discussed.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"2014 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Per O. Å. Persson, Johanna Rosen, Ivan Petrov, Justinas Palisaitis
Near-stoichiometric chromium diboride films were subject to in situ annealing inside a scanning transmission electron microscope to access the thermal behavior of the film and embedded structural planar defects. Independent of films’ stoichiometry, the planar defects were unaffected by the applied heat treatments. On the contrary, the interfaces between the boron-rich tissue phase and the CrB2 phase were reshaped in the overstoichometric CrB2 film. At high temperatures, diffusion of contact metal species (platinum) from the focused ion beam sample preparation was triggered, with subsequent migration onto the sample. This resulted in the formation of metal-rich regions as directly observed and characterized at the atomic level. We determined that platinum did not react with the diboride structure but is accommodated by various defects present in the film.
{"title":"Exploring the thermal behavior and diffusive functionality of structural defects and phase boundaries in near-stoichiometric chromium diborides by in situ scanning transmission electron microscopy","authors":"Per O. Å. Persson, Johanna Rosen, Ivan Petrov, Justinas Palisaitis","doi":"10.1116/6.0003389","DOIUrl":"https://doi.org/10.1116/6.0003389","url":null,"abstract":"Near-stoichiometric chromium diboride films were subject to in situ annealing inside a scanning transmission electron microscope to access the thermal behavior of the film and embedded structural planar defects. Independent of films’ stoichiometry, the planar defects were unaffected by the applied heat treatments. On the contrary, the interfaces between the boron-rich tissue phase and the CrB2 phase were reshaped in the overstoichometric CrB2 film. At high temperatures, diffusion of contact metal species (platinum) from the focused ion beam sample preparation was triggered, with subsequent migration onto the sample. This resulted in the formation of metal-rich regions as directly observed and characterized at the atomic level. We determined that platinum did not react with the diboride structure but is accommodated by various defects present in the film.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"66 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140056177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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