Journal of Vacuum Science & Technology B最新文献

{"title":"One-step formation of ZrON thin film on surface of carbon fine particles for membrane electrode assembly","authors":"Yudai Aihara, Takashi Iida, Kakeru Kodama, Hiroshi Iwata, Takao Sekiya","doi":"10.1116/6.0003542","DOIUrl":"https://doi.org/10.1116/6.0003542","url":null,"abstract":"Zirconium nitride and oxynitride films were deposited on alumina or carbon particles by reactive sputtering using a magnetron sputtering apparatus with a Zr hollow cylindrical target and a vibrating equipment with heating capability. The vibrating equipment developed in this study was effective if the particles are spherical and highly monodisperse. Uniform film deposition was achieved over the entire surface of highly monodisperse spherical alumina particles using the vibrating equipment during deposition. Pure ZrN crystalline layers was deposited under Ar and N2 gas flows with heating on XC-72 carbon powder particles removed adsorbed oxygen. Energy dispersive x-ray spectroscopy mapping analysis for deposited XC-72 carbon particles showed ubiquitous film deposition on agglomerated particles regardless of vibration during sputtering. Uniform film deposition with vibrating equipment was achieved on the entire surface of CGB-10 particles with more spherical and monodisperse than XC-72 but precipitated crystalline phase depended on unintentional oxygen chemisorbed on the particles. Addition and increase in flow rate of oxygen to the sputtering gas resulted in the formation of desired crystalline phase, Zr2ON2, Zr7O8N4, and monoclinic ZrO2, precipitated in the film using CGB-10 particles with chemisorbed oxygen removed. Current density for oxygen reduction reaction measured for MEA made from CGB-10 particles with ZrON-based crystals deposited was larger than that for thin film deposited on a carbon plate substrate.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"27 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141053289","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":"Role of tin clustering in band structure and thermodynamic stability of GeSn by atomistic modeling","authors":"S. Karthikeyan, M. Hudait","doi":"10.1116/6.0003563","DOIUrl":"https://doi.org/10.1116/6.0003563","url":null,"abstract":"Synthesis of device-quality GeSn materials with higher Sn compositions is hindered by various factors, such as Sn segregation, clustering, and short-range ordering effects. In the present work, the impact of the clustering of Sn atoms in a GeSn semiconductor alloy was studied by density functional theory using SG15 pseudopotentials in a Synopsys QuantumATK tool, where the thermodynamic stability, effective band structure, indirect and direct bandgaps, and density of states (DOS) were computed to highlight the difference between a cluster-free random GeSn alloy and a GeSn alloy with Sn–Sn clusters. A 54-atom bulk Ge1–xSnx (x = 3.71%–27.77%) supercell was constructed with cluster-free and a first nearest neighbor Sn–Sn clustered GeSn alloy at each composition for this work. Computation using the generalized gradient approximation exchange-correlation functional showed that the thermodynamic stability of GeSn was reduced due to the clustering of Sn, which increased the formation energy of the GeSn alloys by increasing the Hartree potential energy and exchange-correlation energy. Moreover, with the effective band structure of the GeSn material at a Sn composition of ∼22%, both direct (Eg,Γ) and indirect (Eg,L) bandgaps decreased by a large margin of 40.76 and 120.17 meV, respectively, due to Sn–Sn clustering. On the other hand, Eg,Γ and Eg,L decrease is limited to 0.5 and 12.8 meV, respectively, for Sn composition of ∼5.6%. Similar impacts were observed on DOS, in an independent computation without deducing from the electronic band structure, where the width of the forbidden band reduces due to the clustering of Sn atoms in GeSn. Moreover, using the energy bandgaps of GeSn computed with the assumption of it being a random alloy having well-dispersed Sn atoms needs revision by incorporating clustering to align with the experimentally determined bandgap. This necessitates incorporating the effect of Sn atoms clustered together at varying distributions based on experimental characterization techniques such as atom probe tomography or extended x-ray absorption fine structure to substantiate the energy bandgap of the GeSn alloy at a particular composition with precision. Hence, considering the effect of Sn clusters during material characterization, beginning with the accurate energy bandgap characterization of GeSn would help in mitigating the effect of process variations on the performance characteristics of GeSn-based group IV electronic and photonic devices such as varying leakage currents in transistors and photodiodes as well as the deviation from the targeted wavelength of operation in lasers and photodetectors.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141026417","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":"Ordered silicon nanocone fabrication by using pseudo-Bosch process and maskless etching","authors":"Zheng Yan, H. Ekinci, Aixi Pan, Bo Cui","doi":"10.1116/6.0003394","DOIUrl":"https://doi.org/10.1116/6.0003394","url":null,"abstract":"Nanocone arrays are widely employed for applications such as antireflection structures and field emission devices. Silicon nanocones are typically obtained by an etching process, but the profile is hard to attain because anisotropic dry etching generally gives vertical or only slightly tapered sidewall profiles, and isotropic dry plasma etching gives curved sidewalls. In this work, we report the fabrication of cone structures by using masked etching followed by maskless etching techniques. The silicon structure is first etched using fluorine-based plasma under the protection of a hard metal mask, with a tapered or vertical sidewall profile. The mask is then removed, and maskless etching with an optimized nonswitching pseudo-Bosch recipe is applied to achieve the cone structure with a sharp apex. The gas flow ratio of C4F8 and SF6 is significantly increased from 38:22 (which creates a vertical profile) to 56:4, creating a taper angle of approximately 80°. After subsequent maskless etching, the sidewall taper angle is decreased to 74°, and the structure is sharpened to give a pointed apex. The effect of an oxygen cleaning step is also studied. With the introduction of periodic oxygen plasma cleaning steps, both the etch rate and surface smoothness are greatly improved. Lastly, it was found that the aspect ratio-dependent etching effect becomes prominent for dense patterns of cone arrays, with a greatly reduced etch depth at a 600 nm pitch array compared to a 1200 nm pitch array.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"173 S391","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141039939","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":"Parylene-C-based flexible organic thin-film transistors and their reliability improvement using SU-8 passivation","authors":"Ah-Hyun Hong, Yu Jung Park, J. Seo, Yoon Kim, Dong-Wook Park","doi":"10.1116/5.0197032","DOIUrl":"https://doi.org/10.1116/5.0197032","url":null,"abstract":"Flexible and biocompatible organic thin-film transistors (OTFTs) can be well-suited for biological applications due to their compatibility with biomaterials. In this study, flexible OTFTs were fabricated with a Parylene-C substrate and gate dielectric, a material known for its flexibility and biocompatibility. We used poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] as organic channel material. To ensure the longevity and protection of the channel, SU-8, known for its biocompatibility and transparency, effectively safeguarded the OTFT and ensured its sustained operation. Flexible OTFTs were affixed to a curved fixture, referred to as a “curved condition.” The device parameters at −20 V of VD in the curved condition shows an Ion/off ratio of 3.5 × 104, threshold voltage (VTH) of −0.42 V, and mobility of 0.003 cm2/V s. The Parylene-C-based OTFT with SU-8 passivation demonstrated reliability by maintaining performance under curved conditions for 40 days. The results show that the proposed device is suitable for flexible electronics and sensor applications.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"101 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141056878","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":"Effects of working pressure during magnetron sputtering on thermoelectric performance of flexible p-type Bi0.5Sb1.5Te3 thin films","authors":"Ding Hu, Shaojun Liang, Yichun He, Rensheng Zhang, Song Yue","doi":"10.1116/6.0003631","DOIUrl":"https://doi.org/10.1116/6.0003631","url":null,"abstract":"The influence of argon working pressure during magnetron sputtering on thermoelectric properties has been investigated on p-type Bi0.5Sb1.5Te3 flexible films deposited at various working pressures in the range from 2 to 5 Pa. The microstructure and orientations, atomic compositions, and carrier concentration could be regulated by adjusting the working pressure, due to the size-dependent inhibition of the deposition of the sputtered Bi, Sb, and Te atoms from argon ions. Profiting from the occurrence of the (006) orientation, the nearest stoichiometric ratio, the highest carrier concentration and mobility, and the quantum confinement effect, the film deposited at 4 Pa displays the maximum power factor of 1095 μW m−1 K−2 at 360 K. These results suggest that the electrical transport properties of the sputtered flexible thermoelectric thin films can be synergistically optimized by selecting an appropriate working pressure.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"12 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141044498","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":"Evolution of hard carbon layers on Ti-45Al-2Nb-2Mn-1B by plasma enhanced chemical vapor deposition of hydrocarbons and hydrogen","authors":"A. Rastkar, Mehdi Sadri Kandjani","doi":"10.1116/6.0003483","DOIUrl":"https://doi.org/10.1116/6.0003483","url":null,"abstract":"Extension of pulsed DC plasma enhanced CVD (PECVD) of carbon from hydrocarbons resulted in thick hard carbon layers on Ti-45Al-2Nb-2Mn-1B. PECVD for less than 2 h led to the formation of surface interlayers of TiC and Ti2AlC compounds under the hard carbon layer. After 5 h until 20 h, the formation of carbons layers surpassed the growth of TiC and Ti2AlC layers and resulted in a thicker hard carbon layer. This can be explained with the deceleration of carbon diffusion into the base alloy that resulted in the accumulation of a hard structure of carbon on the outer surface. The thickness of the hard carbon layers reached up to ∼40 μm, which were revealed using SEM microcopy. The hardness on the outer surface of hard carbon layer was around 600–1500 HV0.5 (5.88–14.71 GPa). EDX analysis across the surface layers showed ∼50–100 at. % carbon on the outermost layers. Raman spectroscopy of carbon layers showed sp3 (D) and sp2 (G) peaks of carbon at ∼1330 and ∼1560 cm−1 and peaks of TiC at ∼200 cm−1 peaks.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"41 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141045514","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":"Effects of graphene doping and gas adsorption on the peak positions of graphene plasmon resonance and adsorbate infrared absorption","authors":"Jongpil Ye","doi":"10.1116/6.0003588","DOIUrl":"https://doi.org/10.1116/6.0003588","url":null,"abstract":"The peak positions of graphene plasmon resonance can be controlled to overlap with those of the infrared absorption spectra of gas molecules, allowing highly sensitive detection and identification by graphene nanoribbons. In this study, we investigate the adsorption of gas molecules, including SO2, SO3, H2S, and NH3, on graphene and characterize its effects on the relative positions of the two peaks using density functional theory and the finite difference time domain method. It is demonstrated that the binding energies are stronger, and the amounts of charge transfer are greater in the case of SO2 and SO3 adsorbed on n-doped graphene than in other cases. Electron acceptance by SO2 and SO3 adsorbates on n-doped graphene redshifts the graphene plasmon resonance peaks and their stretching and wagging infrared absorption peaks. However, the former is significantly further redshifted, leading to narrower peak-position-matching ribbon widths in n-doped graphene than in p-doped graphene. The amounts of charge transfer are relatively small regardless of the doping type in the case of NH3 and H2S, mitigating the doping-type dependence compared to SO2 and SO3. The wagging peaks of NH3 on n-doped graphene are shown to be further blueshifted than on p-doped graphene, rendering their peak-position-matching ribbon widths further closer to each other. These results suggest that the effects of doping and adsorption on the two types of peaks should be considered to optimize the performance of graphene plasmon-based gas sensing and identification.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"101 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141037599","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":"Fabrication of silicon sharp nanocones using dry etch with periodic oxygen plasma shrinking and wet etch","authors":"Renqiang Kang, Aixi Pan, Bo Cui","doi":"10.1116/6.0003516","DOIUrl":"https://doi.org/10.1116/6.0003516","url":null,"abstract":"Silicon (Si) nanocones have a wide range of applications in microelectromechanical systems and nanoelectromechanical systems. There is an increasing demand for precise control over the size and shape of nanocones. This paper proposed a novel method combining Si dry etch with periodic oxygen plasma shrinking, wet etch, and oxidation sharpening to achieve well-defined sharp Si nanocones. First, the standard Bosch process was employed to create the base part of nanocones. Second, two alternating steps of etching with sulfur hexafluoride/octafluorocyclobutane plasma and photoresist shrinkage with oxygen plasma were used to form the cone-shaped structures on top of the cylindrical bases. Third, to obtain a sharp tip, wet etching was carried out in either potassium hydroxide or a nitric acid/hydrofluoric (HF) acid mixture. To further sharpen the Si tips, thermal oxidation and HF dipping were conducted and the apex of nanocones can be down to 20 nm. This technique provides a cost-effective way to manufacture nanocones for various applications.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"55 44","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140656448","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":"Thermal analysis with high accuracy of multi-beam mask fabrication","authors":"Yanjun Zhang, Kaijun Dong, Zhuming Liu, Delong Chen","doi":"10.1116/6.0003477","DOIUrl":"https://doi.org/10.1116/6.0003477","url":null,"abstract":"For a 7 nm technology node and beyond, multi-beam mask fabrication based on charged particles has attracted attention widely and shows great advantages in terms of throughput. However, the heating effect during mask writing is a serious problem and makes deformation error. To address this issue, an accurate analysis of heating with multi-beam writing is necessary. In this study, the thermal effects of electron beams on a mask during writing time (exposure time and nonexposure time) were simulated with a finite element numerical method. The variation in the temperature field with two writing paths (S-shaped and E-shaped) was analyzed. A comparative analysis of the mask’s deformation under different writing paths was conducted. Numerical research shows that the thermal analysis method in this study provides a guide for optimizing the process parameters of mask fabrication.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"57 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140656427","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":"Planar microcoil arrays for in vitro cellular-level micromagnetic activation of neurons","authors":"Renata Saha, O. J. Benally, S. Faramarzi, Robert P. Bloom, Kai Wu, Denis Tonini, Maple L Shiao, Susan A. Keirstead, Walter C Low, T. Netoff, Jian‐Ping Wang","doi":"10.1116/6.0003362","DOIUrl":"https://doi.org/10.1116/6.0003362","url":null,"abstract":"In the treatment of neurodegenerative disorders, a potential cure at a single neuron cell resolution is still lacking. Micromagnetic neurostimulation, although in its infancy, is one of the most promising techniques that offer spatially selective activation of neurons through micrometer-sized coils or microcoils (μcoils). Time-varying current drives these μcoils and generates a time-varying magnetic field which in turn induces an electric field to activate the neural tissues. In this work, we report the design and fabrication of planar μcoil arrays, termed Magnetic Patch (MagPatch), for activating single neurons. Using numerical calculations on ANSYS-Maxwell and NEURON, we report an optimized MagPatch array design that exploits the directionality of the induced electric field from the μcoils to enhance spatial selectivity. Each μcoil has an outer dimension of 190 × 190 μm2 and one MagPatch array contains 8 μcoils. For proof-of-concept design and development, the MagPatch array has been fabricated on Si-substrates using Ti, Au, and Si3N4 to ensure preliminary biocompatibility. They were then encapsulated in Parylene-C, a waterproof, anti-leakage current coating, thereby ensuring basic surface biocompatibility. Human neuroblastoma cells were cultured directly on the surface encapsulated MagPatch, and calcium fluorescence imaging was used to assess cell functionality. The impact of scaling the dimensions of the μcoil in the MagPatch array on electrical characteristics, Q-factor, and thermal effects on neural tissues from these μcoils have also been discussed.","PeriodicalId":282302,"journal":{"name":"Journal of Vacuum Science & Technology B","volume":"42 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140667107","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}