Nicolas Le Brun, Gilles Cunge, Pascal Gouraud, C. Petit-Etienne, Linda Parmigiani, Stéphane Allegret-Maret, Denis Guiheux, Jonathan S. Steckel
Many consumer products used daily contain sensors and image sensors (smartphones, cars, automated tools, etc.). There is a growing demand to enhance the capabilities of industrial products to probe their environment more efficiently, i.e., under difficult conditions (smoke, darkness, etc.). One solution is to extend the capabilities of image sensors to detect light toward the near-infrared and short-wave infrared (SWIR) regions. Because silicon has weak absorption properties in the infrared, especially in the SWIR region, manufacturers are investigating the use of new materials to build these sensors. To this end, colloidal quantum dot (QD) thin films made from the assembly of PbS nanoparticles have emerged as promising materials. They offer tunable bandgaps, favorable absorption properties, and scalability in production. However, patterning the active parts of photodiodes by plasma etching of this new material presents challenges. The etching chemistry must be selected to volatilize Pb and S without modifying the unetched active part of the PbS QD photodiode, and the etching profile should be anisotropic. In this study, we have screened several plasma operating conditions (power, pressure, and temperature) in various chemistries (H2, Cl2, HBr, and N2). To understand the etch mechanisms and profiles, ToF-SIMS and TEM/energy dispersive x-ray were employed. Our findings reveal that halogen-based plasmas cause QD material deterioration through Cl or Br diffusion deep in the film. While H2 plasmas are efficient to etch PbS QD films, they result in high roughness due to the removal of the carbonated ligands that separate PbS QDs. This ligand etching is followed by QD coalescence leading to significant roughness. However, the addition of N2 to H2 can prevent this phenomenon by forming a diffusion barrier at the surface, resulting in favorable etching characteristics.
{"title":"PbS quantum dot thin film dry etching","authors":"Nicolas Le Brun, Gilles Cunge, Pascal Gouraud, C. Petit-Etienne, Linda Parmigiani, Stéphane Allegret-Maret, Denis Guiheux, Jonathan S. Steckel","doi":"10.1116/6.0003335","DOIUrl":"https://doi.org/10.1116/6.0003335","url":null,"abstract":"Many consumer products used daily contain sensors and image sensors (smartphones, cars, automated tools, etc.). There is a growing demand to enhance the capabilities of industrial products to probe their environment more efficiently, i.e., under difficult conditions (smoke, darkness, etc.). One solution is to extend the capabilities of image sensors to detect light toward the near-infrared and short-wave infrared (SWIR) regions. Because silicon has weak absorption properties in the infrared, especially in the SWIR region, manufacturers are investigating the use of new materials to build these sensors. To this end, colloidal quantum dot (QD) thin films made from the assembly of PbS nanoparticles have emerged as promising materials. They offer tunable bandgaps, favorable absorption properties, and scalability in production. However, patterning the active parts of photodiodes by plasma etching of this new material presents challenges. The etching chemistry must be selected to volatilize Pb and S without modifying the unetched active part of the PbS QD photodiode, and the etching profile should be anisotropic. In this study, we have screened several plasma operating conditions (power, pressure, and temperature) in various chemistries (H2, Cl2, HBr, and N2). To understand the etch mechanisms and profiles, ToF-SIMS and TEM/energy dispersive x-ray were employed. Our findings reveal that halogen-based plasmas cause QD material deterioration through Cl or Br diffusion deep in the film. While H2 plasmas are efficient to etch PbS QD films, they result in high roughness due to the removal of the carbonated ligands that separate PbS QDs. This ligand etching is followed by QD coalescence leading to significant roughness. However, the addition of N2 to H2 can prevent this phenomenon by forming a diffusion barrier at the surface, resulting in favorable etching characteristics.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"76 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140729508","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}
Yukito Ozawa, Rai Hiranabe, Shinpei Shimono, Qiuzhi Liu, K. Okimura
We fabricated stand-alone flexible vanadium dioxide (VO2) films on 10 μm-thick polyimide (PI) sheets with large insulator metal transition (IMT). Zinc oxide (ZnO)-nanorods grown by the chemical synthesis method as a buffer layer between VO2 and PI realized IMT with resistance change nearly three orders of magnitude. Highly bm axis oriented VO2 films on ZnO_NR buffered PI realized switching of 1450 nm infrared-light more than 40%. The transmittance values at a metallic phase below 2% at temperatures higher than 70 °C were quite low, suggesting high potential for various applications in the infrared and terahertz wavelength region. Number densities of cracks in the VO2 films were estimated from the scanning electron microscopy (SEM) images. Quantitative relation between crack density and the bias voltage suggested the strain-induced formation of cracks in the VO2 films prepared by biased-sputtering. As for flexible performance, the stand-alone VO2 films on PI were directed to bending examinations up to 2000 times. The ZnO-nanorods buffered VO2 films on PI showed high durability for maintaining the superior IMT characteristics. The results obtained in this study show a way to realize practical flexibility of VO2 stand-alone sheets which are able to apply for a variety of fields utilizing switching of VO2.
{"title":"Flexible VO2 films grown on ZnO-nanorod buffered polyimide sheets with large insulator metal transition: Evaluation of flexible performance","authors":"Yukito Ozawa, Rai Hiranabe, Shinpei Shimono, Qiuzhi Liu, K. Okimura","doi":"10.1116/6.0003378","DOIUrl":"https://doi.org/10.1116/6.0003378","url":null,"abstract":"We fabricated stand-alone flexible vanadium dioxide (VO2) films on 10 μm-thick polyimide (PI) sheets with large insulator metal transition (IMT). Zinc oxide (ZnO)-nanorods grown by the chemical synthesis method as a buffer layer between VO2 and PI realized IMT with resistance change nearly three orders of magnitude. Highly bm axis oriented VO2 films on ZnO_NR buffered PI realized switching of 1450 nm infrared-light more than 40%. The transmittance values at a metallic phase below 2% at temperatures higher than 70 °C were quite low, suggesting high potential for various applications in the infrared and terahertz wavelength region. Number densities of cracks in the VO2 films were estimated from the scanning electron microscopy (SEM) images. Quantitative relation between crack density and the bias voltage suggested the strain-induced formation of cracks in the VO2 films prepared by biased-sputtering. As for flexible performance, the stand-alone VO2 films on PI were directed to bending examinations up to 2000 times. The ZnO-nanorods buffered VO2 films on PI showed high durability for maintaining the superior IMT characteristics. The results obtained in this study show a way to realize practical flexibility of VO2 stand-alone sheets which are able to apply for a variety of fields utilizing switching of VO2.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"198 S580","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140730735","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}
Changhui Li, Jiajun Zhu, Juanrui Hu, Leilei Hao, Bin Ji, L. Fu, Wulin Yang, Lingping Zhou
This work modified the surface of copper using physical vapor deposition and investigated the wear behavior of the modified copper at low load and sliding speed. The results of the study showed that the adhesion between the thin film prepared using the ion beam deposition technique and the substrate was insufficient, leading to an increased wear rate of copper after surface modification. However, when carbon particles were injected using ion beam-assisted bombardment, the friction properties of copper were significantly improved, with a decrease in wear rate from 1.6 × 10−4 to 8 × 10−6 mm3/N m and a 40% reduction in friction coefficient. This improvement can be attributed to the amorphous carbon layer on the copper surface, as well as the injection of carbon particles into the substrate, which enhanced the adhesion between the film and the substrate. Furthermore, a continuous copper oxide film formed during the friction and wear process, providing lubrication and protection to the substrate in conjunction with the amorphous carbon layer. Additionally, the primary wear mechanism of copper shifted from abrasive and adhesive wear to oxidation wear after ion beam-assisted bombardment with carbon injection. This study provides new insights and methods for material design and engineering applications by investigating the effects of ion beam-assisted bombardment technology on the wear resistance of copper materials.
{"title":"Friction and wear behavior of C implanted copper via ion beam-assisted bombardment","authors":"Changhui Li, Jiajun Zhu, Juanrui Hu, Leilei Hao, Bin Ji, L. Fu, Wulin Yang, Lingping Zhou","doi":"10.1116/6.0003495","DOIUrl":"https://doi.org/10.1116/6.0003495","url":null,"abstract":"This work modified the surface of copper using physical vapor deposition and investigated the wear behavior of the modified copper at low load and sliding speed. The results of the study showed that the adhesion between the thin film prepared using the ion beam deposition technique and the substrate was insufficient, leading to an increased wear rate of copper after surface modification. However, when carbon particles were injected using ion beam-assisted bombardment, the friction properties of copper were significantly improved, with a decrease in wear rate from 1.6 × 10−4 to 8 × 10−6 mm3/N m and a 40% reduction in friction coefficient. This improvement can be attributed to the amorphous carbon layer on the copper surface, as well as the injection of carbon particles into the substrate, which enhanced the adhesion between the film and the substrate. Furthermore, a continuous copper oxide film formed during the friction and wear process, providing lubrication and protection to the substrate in conjunction with the amorphous carbon layer. Additionally, the primary wear mechanism of copper shifted from abrasive and adhesive wear to oxidation wear after ion beam-assisted bombardment with carbon injection. This study provides new insights and methods for material design and engineering applications by investigating the effects of ion beam-assisted bombardment technology on the wear resistance of copper materials.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"81 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140736242","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}
Corbin Feit, Udit Kumar, Md. Rafiqul Islam, Luis Tomar, S. Berriel, J. Gaskins, Patrick E. Hopkins, Sudipta Seal, Parag Banerjee
Atomic layer deposition (ALD) of ruthenium (Ru) is being investigated for next generation interconnects and conducting liners for copper metallization. However, integration of ALD Ru with diffusion barrier refractory metal nitrides, such as tantalum nitride (TaN), continues to be a challenge due to its slow nucleation rates. Here, we demonstrate that an ultraviolet-ozone (UV-O3) pretreatment of TaN leads to an oxidized surface that favorably alters the deposition characteristics of ALD Ru from islandlike to layer-by-layer growth. The film morphology and properties are evaluated via spectroscopic ellipsometry, atomic force microscopy, electrical sheet resistance measurements, and thermoreflectance. We report a 1.83 nm continuous Ru film with a roughness of 0.19 nm and a sheet resistance of 10.8 KΩ/□. The interface chemistry between TaN and Ru is studied by x-ray photoelectron spectroscopy. It is shown that UV-O3 pretreatment, while oxidizing TaN, enhances Ru film nucleation and limits further oxidation of the underlying TaN during ALD. An oxygen “gettering” mechanism by TaN is proposed to explain reduced oxygen content in the Ru film and higher electrical conductivity compared to Ru deposited on native-TaN. This work provides a simple and effective approach using UV-O3 pretreatment for obtaining sub-2 nm, smooth, and conducting Ru films on TaN surfaces.
目前正在研究将钌（Ru）原子层沉积（ALD）用于下一代互连器件和铜金属化导电衬里。然而，由于氮化钽（TaN）的成核速度较慢，将 ALD Ru 与扩散屏障难熔金属氮化物（如氮化钽）进行整合仍是一项挑战。在这里，我们证明了对 TaN 进行紫外线-臭氧（UV-O3）预处理会导致表面氧化，从而有利地改变 ALD Ru 的沉积特性，使其从岛状生长变为逐层生长。我们通过光谱椭偏仪、原子力显微镜、片状电阻测量和热反射来评估薄膜的形态和特性。我们报告了 1.83 nm 的连续 Ru 薄膜，其粗糙度为 0.19 nm，薄层电阻为 10.8 KΩ/□。通过 X 射线光电子能谱研究了 TaN 和 Ru 之间的界面化学性质。结果表明，UV-O3 预处理在氧化 TaN 的同时，还增强了 Ru 薄膜的成核，并在 ALD 过程中限制了下层 TaN 的进一步氧化。与沉积在原生氮化钽上的 Ru 相比，TaN 的氧气 "获取 "机制可解释 Ru 膜中氧气含量的降低和更高的导电率。这项工作提供了一种简单有效的方法，即使用 UV-O3 预处理，在 TaN 表面获得亚 2 纳米、光滑和导电的 Ru 薄膜。
{"title":"Surface treatment of TaN for sub-2 nm, smooth, and conducting atomic layer deposition Ru films","authors":"Corbin Feit, Udit Kumar, Md. Rafiqul Islam, Luis Tomar, S. Berriel, J. Gaskins, Patrick E. Hopkins, Sudipta Seal, Parag Banerjee","doi":"10.1116/6.0003440","DOIUrl":"https://doi.org/10.1116/6.0003440","url":null,"abstract":"Atomic layer deposition (ALD) of ruthenium (Ru) is being investigated for next generation interconnects and conducting liners for copper metallization. However, integration of ALD Ru with diffusion barrier refractory metal nitrides, such as tantalum nitride (TaN), continues to be a challenge due to its slow nucleation rates. Here, we demonstrate that an ultraviolet-ozone (UV-O3) pretreatment of TaN leads to an oxidized surface that favorably alters the deposition characteristics of ALD Ru from islandlike to layer-by-layer growth. The film morphology and properties are evaluated via spectroscopic ellipsometry, atomic force microscopy, electrical sheet resistance measurements, and thermoreflectance. We report a 1.83 nm continuous Ru film with a roughness of 0.19 nm and a sheet resistance of 10.8 KΩ/□. The interface chemistry between TaN and Ru is studied by x-ray photoelectron spectroscopy. It is shown that UV-O3 pretreatment, while oxidizing TaN, enhances Ru film nucleation and limits further oxidation of the underlying TaN during ALD. An oxygen “gettering” mechanism by TaN is proposed to explain reduced oxygen content in the Ru film and higher electrical conductivity compared to Ru deposited on native-TaN. This work provides a simple and effective approach using UV-O3 pretreatment for obtaining sub-2 nm, smooth, and conducting Ru films on TaN surfaces.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"103 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140748775","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}
Atefeh Fathzadeh, Philippe Bezard, Maxime Darnon, Inge Manders, T. Conard, I. Hoflijk, Frederic Lazzarino, S. de Gendt
Atomic layer etching (ALE) schemes are often deemed economically unviable due to their slow pace and are not suited for every material/hard-mask combination. Conversely, plasma etching presents pattern profile challenges because of its inability to independently control ion and neutral flux. In this work, we introduce a new cyclic transient-based process, called transient-assisted plasma etching (TAPE). A cycle of TAPE is a short exposure step to a sustained flow of reactant before the reactant gas injection is stopped in the second step, resulting in a plasma transient. As the plasma ignites and a substantial amount of etchant remains, a chemically driven etching process occurs, akin to conventional etching. Later in the transient, the modified surface is exposed to a reduced etchant quantity and a sustained ion bombardment, in a similar way to ALE. The cointegration of conventional etching and atomic layer etching allows interesting compromises between etch control and processing time. Going for a transient plasma allows to provide the time and conditions needed for the necessary plasma-surface interactions to occur in one step. In this perspective, the mechanisms behind etch rate, profile correction, and conservation of surface composition using amorphous carbon, as a benchmark, are discussed.
原子层蚀刻 (ALE) 方案由于速度慢，通常被认为在经济上不可行，而且并不适合每种材料/硬掩膜组合。相反，等离子刻蚀由于无法独立控制离子和中性通量，因此对图案轮廓提出了挑战。在这项工作中，我们引入了一种基于循环瞬态的新工艺，称为瞬态辅助等离子刻蚀（TAPE）。TAPE 的一个循环是在第二步停止注入反应物气体之前的一个短暂的反应物持续流暴露步骤，从而产生等离子体瞬态。当等离子体点燃并残留大量蚀刻剂时，就会发生化学驱动的蚀刻过程，类似于传统的蚀刻。在瞬态过程的后期，改性表面会暴露在蚀刻液数量减少和持续离子轰击的环境中，这与 ALE 类似。传统蚀刻和原子层蚀刻的结合可以在蚀刻控制和加工时间之间做出有趣的妥协。采用瞬态等离子体可为一步完成必要的等离子体-表面相互作用提供所需的时间和条件。从这个角度出发，以无定形碳为基准，讨论了蚀刻速率、轮廓校正和表面成分保持背后的机制。
{"title":"Transient-assisted plasma etching (TAPE): Concept, mechanism, and prospects","authors":"Atefeh Fathzadeh, Philippe Bezard, Maxime Darnon, Inge Manders, T. Conard, I. Hoflijk, Frederic Lazzarino, S. de Gendt","doi":"10.1116/6.0003380","DOIUrl":"https://doi.org/10.1116/6.0003380","url":null,"abstract":"Atomic layer etching (ALE) schemes are often deemed economically unviable due to their slow pace and are not suited for every material/hard-mask combination. Conversely, plasma etching presents pattern profile challenges because of its inability to independently control ion and neutral flux. In this work, we introduce a new cyclic transient-based process, called transient-assisted plasma etching (TAPE). A cycle of TAPE is a short exposure step to a sustained flow of reactant before the reactant gas injection is stopped in the second step, resulting in a plasma transient. As the plasma ignites and a substantial amount of etchant remains, a chemically driven etching process occurs, akin to conventional etching. Later in the transient, the modified surface is exposed to a reduced etchant quantity and a sustained ion bombardment, in a similar way to ALE. The cointegration of conventional etching and atomic layer etching allows interesting compromises between etch control and processing time. Going for a transient plasma allows to provide the time and conditions needed for the necessary plasma-surface interactions to occur in one step. In this perspective, the mechanisms behind etch rate, profile correction, and conservation of surface composition using amorphous carbon, as a benchmark, are discussed.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"56 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140748553","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}
T. P. Menasuta, Kevin A. Grossklaus, John H. McElearney, Thomas E. Vandervelde
We investigate the surface morphologies of two series of homoepitaxial GaSb(100) thin films grown on GaSb(100) substrates by molecular beam epitaxy in a Veeco GENxplor system. The first series was grown at temperatures ranging from 290 to 490°C and serves as a control. The second series was grown using the same growth parameters with bismuth used as a surfactant during growth. We compared the two series to examine the impacts of bismuth over the range of growth temperatures on the GaSb surface morphologies using atomic force microscopy and the film properties using Raman spectroscopy and scanning electron microscopy. High-resolution x-ray diffraction was performed to confirm that bismuth was not incorporated into the films. We found that the morphological evolution of the GaSb series grown without bismuth is consistent with the standard surface nucleation theory and identified the 2D-3D transition temperature as close to 290° C. In contrast, the presence of a Bi surfactant during growth was found to significantly alter the surface morphology and prevent undesired 3D islands at low temperatures. We also observed a preference for hillocks over step morphology at high growth temperatures, antistep bunching effects at intermediate temperatures, and the evolution from step-meandering to mound morphologies at low temperatures. This morphological divergence from the first series indicates that bismuth significantly increases in the 2D Erlich–Schwöebel potential barrier of the atomic terraces, inducing an uphill adatom flux that can smoothen the surface. Our findings demonstrate that bismuth surfactant can improve the surface morphology and film structure of low-temperature grown GaSb. Bismuth surfactant may also improve other homoepitaxial III-V systems grown in nonideal conditions.
{"title":"Bismuth surfactant enhancement of surface morphology and film quality of MBE-grown GaSb(100) thin films over a wide range of growth temperatures","authors":"T. P. Menasuta, Kevin A. Grossklaus, John H. McElearney, Thomas E. Vandervelde","doi":"10.1116/6.0003458","DOIUrl":"https://doi.org/10.1116/6.0003458","url":null,"abstract":"We investigate the surface morphologies of two series of homoepitaxial GaSb(100) thin films grown on GaSb(100) substrates by molecular beam epitaxy in a Veeco GENxplor system. The first series was grown at temperatures ranging from 290 to 490°C and serves as a control. The second series was grown using the same growth parameters with bismuth used as a surfactant during growth. We compared the two series to examine the impacts of bismuth over the range of growth temperatures on the GaSb surface morphologies using atomic force microscopy and the film properties using Raman spectroscopy and scanning electron microscopy. High-resolution x-ray diffraction was performed to confirm that bismuth was not incorporated into the films. We found that the morphological evolution of the GaSb series grown without bismuth is consistent with the standard surface nucleation theory and identified the 2D-3D transition temperature as close to 290° C. In contrast, the presence of a Bi surfactant during growth was found to significantly alter the surface morphology and prevent undesired 3D islands at low temperatures. We also observed a preference for hillocks over step morphology at high growth temperatures, antistep bunching effects at intermediate temperatures, and the evolution from step-meandering to mound morphologies at low temperatures. This morphological divergence from the first series indicates that bismuth significantly increases in the 2D Erlich–Schwöebel potential barrier of the atomic terraces, inducing an uphill adatom flux that can smoothen the surface. Our findings demonstrate that bismuth surfactant can improve the surface morphology and film structure of low-temperature grown GaSb. Bismuth surfactant may also improve other homoepitaxial III-V systems grown in nonideal conditions.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"43 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140767080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas Vincent, Damien Coutancier, Pia Dally, Mirella Al Katrib, M. Frégnaux, Stefania Cacovich, F. Donsanti, Armelle Yaïche, Karim Medjoubi, Thomas Guillemot, Marion Provost, Jean Rousset, Muriel Bouttemy, N. Schneider
Access to finely tuned thin films that can act as electron transport layer (ETL) and adapt to the absorber composition and whole cell fabrication process is key to achieve efficient perovskite-based solar cells. In this study, the growth of mixed niobium-titanium oxide (Nb-TiO2) thin films by atomic layer deposition and its use to extract photogenerated electrons is reported. Films were obtained at 200 °C from titanium (IV) i-propoxide, (t-butylimido)tris(diethylamido)niobium(V), and water by introducing Nb2O5 growth cycle in a TiO2 matrix. Process parameters (order of precursor introduction, cycle ratio) were optimized; the growth mechanism and the effective Nb incorporation were investigated by an in situ quartz crystal microbalance and x-ray photoelectron spectroscopy. The composition, morphology, structural, and optoelectronic properties of the as-deposited films were determined using a variety of characterization techniques. As a result, a fine control of the film properties (between TiO2 and Nb2O5 ones) could be achieved by tuning Nb content. To allow a successful implementation in solar devices, a comprehensive annealing study under several conditions (temperatures, various atmospheres) was conducted leading to an evolution of the optical properties due to a morphological change. Ultimately, the incorporation of these 15 nm-thick films in mesoscopic perovskite solar cells as ETL shows an improvement of the cell performances and of their stability with increasing Nb content, in comparison of both TiO2 and Nb2O5 pure compounds, reaching power conversion efficiency up to 18.3% and a stability above 80% of its nominal value after 138 h under illumination.
获得可充当电子传输层（ETL）并适应吸收剂成分和整个电池制造工艺的微调薄膜，是实现高效过氧化物基太阳能电池的关键。本研究报告了通过原子层沉积生长铌钛混合氧化物（Nb-TiO2）薄膜及其用于提取光生电子的情况。薄膜是通过在二氧化钛基体中引入 Nb2O5 生长循环，在 200 °C 下从 i-丙氧基钛 (IV)、(叔丁基亚氨基)三(二乙基氨基)铌 (V) 和水中获得的。对工艺参数（前驱体引入顺序、循环比率）进行了优化；通过原位石英晶体微天平和 X 射线光电子能谱研究了生长机理和铌的有效掺入。利用多种表征技术确定了淀积薄膜的成分、形态、结构和光电特性。因此，通过调整铌的含量，可以实现对薄膜特性（介于 TiO2 和 Nb2O5 之间）的精细控制。为了在太阳能设备中成功应用，我们在多种条件（温度、各种气氛）下进行了全面的退火研究，结果表明，由于形态的变化，光学特性也发生了变化。最终，与二氧化钛和 Nb2O5 纯化合物相比，将这些 15 纳米厚的薄膜作为 ETL 并入介观过氧化物太阳能电池后，随着 Nb 含量的增加，电池的性能和稳定性都得到了改善，功率转换效率高达 18.3%，在光照 138 小时后的稳定性超过其标称值的 80%。
{"title":"Fine tuning of Nb-incorporated TiO2 thin films by atomic layer deposition and application as efficient electron transport layer in perovskite solar cells","authors":"Thomas Vincent, Damien Coutancier, Pia Dally, Mirella Al Katrib, M. Frégnaux, Stefania Cacovich, F. Donsanti, Armelle Yaïche, Karim Medjoubi, Thomas Guillemot, Marion Provost, Jean Rousset, Muriel Bouttemy, N. Schneider","doi":"10.1116/6.0003351","DOIUrl":"https://doi.org/10.1116/6.0003351","url":null,"abstract":"Access to finely tuned thin films that can act as electron transport layer (ETL) and adapt to the absorber composition and whole cell fabrication process is key to achieve efficient perovskite-based solar cells. In this study, the growth of mixed niobium-titanium oxide (Nb-TiO2) thin films by atomic layer deposition and its use to extract photogenerated electrons is reported. Films were obtained at 200 °C from titanium (IV) i-propoxide, (t-butylimido)tris(diethylamido)niobium(V), and water by introducing Nb2O5 growth cycle in a TiO2 matrix. Process parameters (order of precursor introduction, cycle ratio) were optimized; the growth mechanism and the effective Nb incorporation were investigated by an in situ quartz crystal microbalance and x-ray photoelectron spectroscopy. The composition, morphology, structural, and optoelectronic properties of the as-deposited films were determined using a variety of characterization techniques. As a result, a fine control of the film properties (between TiO2 and Nb2O5 ones) could be achieved by tuning Nb content. To allow a successful implementation in solar devices, a comprehensive annealing study under several conditions (temperatures, various atmospheres) was conducted leading to an evolution of the optical properties due to a morphological change. Ultimately, the incorporation of these 15 nm-thick films in mesoscopic perovskite solar cells as ETL shows an improvement of the cell performances and of their stability with increasing Nb content, in comparison of both TiO2 and Nb2O5 pure compounds, reaching power conversion efficiency up to 18.3% and a stability above 80% of its nominal value after 138 h under illumination.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"53 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140367358","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}
Daniel Hiller, Frans Munnik, Julian López-Vidrier, D. Solonenko, J. Reif, M. Knaut, Oliver Thimm, N.E. Grant
Atomic layer-deposited (ALD) TiO2 thin films on silicon were deposited using titanium tetrachloride (TiCl4), titanium tetraisopropoxide (TTIP), and tetrakis(dimethylamino)titanium (TDMAT) together with water vapor as the oxidant at temperatures ranging between 75 and 250 °C. The Si surface passivation quality of as-deposited and isothermally annealed samples was compared using photoconductance lifetime measurements in order to calculate their effective surface recombination velocities Seff. A low Seff of 3.9 cm/s (J0s=24fA/cm2) is achieved for as-deposited TiCl4-TiO2 at 75 °C when a chemically grown (i.e., from RCA cleaning) SiOx interface layer is present. Depositing TTIP-TiO2 at 200 °C on a chemically grown SiOx interface layer yields equivalent Seff values; however, in this case, TTIP-TiO2 requires a 5–15 min postdeposition forming gas anneal at 250 °C. In contrast, TDMAT-TiO2 was not found to provide a similar level of passivation with/without a chemically grown SiOx interface layer and postdeposition anneal. Modeling of the effective lifetime curves was used to determine the magnitude of the effective charge densities Qf in the TiO2 films. In all cases, Qf was found to be of the order of ∼1011 q cm−2, meaning field-effect passivation arising from ALD TiO2 is relatively weak. By comparing the material properties of the various TiO2 films using ellipsometry, photothermal deflection spectroscopy, Raman spectroscopy, elastic recoil detection analysis, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we find experimental support for the role of Cl (in conjunction with hydrogen) playing a beneficial role in passivating dangling bond defects at the Si surface. It is concluded that low deposition temperature TiCl4 processes are advantageous, by providing the lowest Seff without any postanneal and a comparatively high growth per cycle (GPC).
{"title":"Comparison of three titanium-precursors for atomic-layer-deposited TiO2 for passivating contacts on silicon","authors":"Daniel Hiller, Frans Munnik, Julian López-Vidrier, D. Solonenko, J. Reif, M. Knaut, Oliver Thimm, N.E. Grant","doi":"10.1116/6.0003309","DOIUrl":"https://doi.org/10.1116/6.0003309","url":null,"abstract":"Atomic layer-deposited (ALD) TiO2 thin films on silicon were deposited using titanium tetrachloride (TiCl4), titanium tetraisopropoxide (TTIP), and tetrakis(dimethylamino)titanium (TDMAT) together with water vapor as the oxidant at temperatures ranging between 75 and 250 °C. The Si surface passivation quality of as-deposited and isothermally annealed samples was compared using photoconductance lifetime measurements in order to calculate their effective surface recombination velocities Seff. A low Seff of 3.9 cm/s (J0s=24fA/cm2) is achieved for as-deposited TiCl4-TiO2 at 75 °C when a chemically grown (i.e., from RCA cleaning) SiOx interface layer is present. Depositing TTIP-TiO2 at 200 °C on a chemically grown SiOx interface layer yields equivalent Seff values; however, in this case, TTIP-TiO2 requires a 5–15 min postdeposition forming gas anneal at 250 °C. In contrast, TDMAT-TiO2 was not found to provide a similar level of passivation with/without a chemically grown SiOx interface layer and postdeposition anneal. Modeling of the effective lifetime curves was used to determine the magnitude of the effective charge densities Qf in the TiO2 films. In all cases, Qf was found to be of the order of ∼1011 q cm−2, meaning field-effect passivation arising from ALD TiO2 is relatively weak. By comparing the material properties of the various TiO2 films using ellipsometry, photothermal deflection spectroscopy, Raman spectroscopy, elastic recoil detection analysis, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we find experimental support for the role of Cl (in conjunction with hydrogen) playing a beneficial role in passivating dangling bond defects at the Si surface. It is concluded that low deposition temperature TiCl4 processes are advantageous, by providing the lowest Seff without any postanneal and a comparatively high growth per cycle (GPC).","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"10 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140366790","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}
Plasma global kinetic model coupled with the Monte Carlo method is used to study the ion transport in HiPIMS Ar/Cr target. The plasma kinetic global model is developed to study the time evolution of neutral, ion, and electron species created in the ionization region. To analyze the ion temporal spectra at the entrance of the mass spectrometer, a simple model based on the Monte Carlo technique is developed to track the ion trajectories from the ionization region to the mass spectrometer. The ion temporal spectra obtained by the global kinetic model in the ionization region are introduced in the Monte Carlo model as input data. The simulation results reveal a temporal shift of the ion spectra as well as their spreading in comparison with those obtained in the ionization region. Such temporal shapes of the ion spectra are more sensitive to the ion temperatures in the ionization region, and the position of the mass spectrometer is connected to the reactor. A satisfactory agreement between simulated ion temporal spectra and those measured by the mass spectrometer is obtained when we have represented the ion population energies by two Maxwellian distributions, where the first one corresponds to the low temperature and the second to the high temperature.
{"title":"Modeling of ion transport from ionization region to entrance of mass spectrometer in HiPIMS argon/Cr target","authors":"J. Zgheib, P.-Y. Jouan, A. Rhallabi","doi":"10.1116/6.0003317","DOIUrl":"https://doi.org/10.1116/6.0003317","url":null,"abstract":"Plasma global kinetic model coupled with the Monte Carlo method is used to study the ion transport in HiPIMS Ar/Cr target. The plasma kinetic global model is developed to study the time evolution of neutral, ion, and electron species created in the ionization region. To analyze the ion temporal spectra at the entrance of the mass spectrometer, a simple model based on the Monte Carlo technique is developed to track the ion trajectories from the ionization region to the mass spectrometer. The ion temporal spectra obtained by the global kinetic model in the ionization region are introduced in the Monte Carlo model as input data. The simulation results reveal a temporal shift of the ion spectra as well as their spreading in comparison with those obtained in the ionization region. Such temporal shapes of the ion spectra are more sensitive to the ion temperatures in the ionization region, and the position of the mass spectrometer is connected to the reactor. A satisfactory agreement between simulated ion temporal spectra and those measured by the mass spectrometer is obtained when we have represented the ion population energies by two Maxwellian distributions, where the first one corresponds to the low temperature and the second to the high temperature.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"66 32","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140364963","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. Kumari, F. Zainab, A. Mishra, W. W. Tjiu, Z. Aabdin, V. R. Singh
The present study is focused on the investigation of the distorted tetragonal phase of mixed spinel oxides, due to their technological relevance in the field of electronics, spintronics, magnetism, catalysis, and electrochemical energy storage. Herein, we report on solgel synthesized multivalent cobalt manganites, CoMn2O4 (CMO), and subjected them to a comprehensive analysis to elucidate their physicochemical characteristics at room temperature. Analysis employing powder x-ray diffraction patterns and electron microscopy (including field-emission scanning electron microscopy and high-resolution transmission electron microscopy) results confirmed the formation of a pure and exceptionally crystalline, distorted tetragonal phase of mixed CMO. Synchrotron-based x-ray absorption spectroscopic (XAS) measurements in the total electron yield mode examined local electronic structures affirming the formation of CMO with uncompensated electronic states involving Co2+, Co3+, Mn2+, Mn3+, and Mn4+ cations. Concurrently, XAS and x-ray magnetic circular dichroism analyses revealed antiferromagnetic coupling within Co and Mn sublattices in CMO, indicating the presence of uncompensated electronic states. Vibrating sample magnetometry results demonstrated clear hysteresis behavior, explicitly indicating the coexistence of super-paramagnetic and canted antiferromagnetic characteristics in CMO, as validated through the Langevin function fitting and x-ray magnetic circular dichroism results. The noticeable absence of saturated magnetization confirmed the high degree of spin canting, primarily stemming from the presence of the Yafet–Kittel spin arrangement.
由于混合尖晶石氧化物在电子学、自旋电子学、磁学、催化和电化学储能等领域具有重要的技术意义，本研究的重点是研究混合尖晶石氧化物的扭曲四方相。在此，我们报告了溶胶法合成的多价钴锰酸盐 CoMn2O4 (CMO)，并对其进行了全面分析，以阐明它们在室温下的物理化学特性。利用粉末 X 射线衍射图样和电子显微镜（包括场发射扫描电子显微镜和高分辨率透射电子显微镜）进行分析的结果证实，混合 CMO 形成了一种纯净且异常结晶的扭曲四方相。基于同步加速器的 X 射线吸收光谱（XAS）测量在电子总产率模式下检查了局部电子结构，确认形成的 CMO 具有涉及 Co2+、Co3+、Mn2+、Mn3+ 和 Mn4+ 阳离子的未补偿电子态。同时，XAS 和 X 射线磁性圆二色性分析揭示了 CMO 中 Co 和 Mn 亚晶格内的反铁磁耦合，表明存在未补偿电子态。振动样品磁力测量结果显示出明显的磁滞行为，明确表明 CMO 中同时存在超顺磁性和斜向反铁磁性特征，朗文函数拟合和 X 射线磁性圆二色性结果也验证了这一点。饱和磁化的明显缺失证实了高度的自旋悬臂，这主要源于 Yafet-Kittel 自旋排列的存在。
{"title":"Strong signature of uncompensated magnetization in frustrated cobalt manganites using x-ray magnetic circular dichroism study","authors":"A. Kumari, F. Zainab, A. Mishra, W. W. Tjiu, Z. Aabdin, V. R. Singh","doi":"10.1116/6.0003417","DOIUrl":"https://doi.org/10.1116/6.0003417","url":null,"abstract":"The present study is focused on the investigation of the distorted tetragonal phase of mixed spinel oxides, due to their technological relevance in the field of electronics, spintronics, magnetism, catalysis, and electrochemical energy storage. Herein, we report on solgel synthesized multivalent cobalt manganites, CoMn2O4 (CMO), and subjected them to a comprehensive analysis to elucidate their physicochemical characteristics at room temperature. Analysis employing powder x-ray diffraction patterns and electron microscopy (including field-emission scanning electron microscopy and high-resolution transmission electron microscopy) results confirmed the formation of a pure and exceptionally crystalline, distorted tetragonal phase of mixed CMO. Synchrotron-based x-ray absorption spectroscopic (XAS) measurements in the total electron yield mode examined local electronic structures affirming the formation of CMO with uncompensated electronic states involving Co2+, Co3+, Mn2+, Mn3+, and Mn4+ cations. Concurrently, XAS and x-ray magnetic circular dichroism analyses revealed antiferromagnetic coupling within Co and Mn sublattices in CMO, indicating the presence of uncompensated electronic states. Vibrating sample magnetometry results demonstrated clear hysteresis behavior, explicitly indicating the coexistence of super-paramagnetic and canted antiferromagnetic characteristics in CMO, as validated through the Langevin function fitting and x-ray magnetic circular dichroism results. The noticeable absence of saturated magnetization confirmed the high degree of spin canting, primarily stemming from the presence of the Yafet–Kittel spin arrangement.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"127 47","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140369598","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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