Journal of Vacuum Science & Technology A最新文献

{"title":"High-performance of ZnO/TiO2 heterostructured thin-film photocatalyst fabricated via atomic layer deposition","authors":"Ji Young Park, Jeong Hwan Han, Byung Joon Choi","doi":"10.1116/6.0003348","DOIUrl":"https://doi.org/10.1116/6.0003348","url":null,"abstract":"Oxide semiconductor is one of the most promising candidates for photocatalysts due to its light absorption ability, electronic properties, and stability. It is used in various applications such as solar-energy conversion, CO2 reduction, and water splitting. In this research, ZnO, TiO2, and ZnO/TiO2 heterostructured thin films are fabricated via atomic layer deposition (ALD), and their photocatalytic performances are evaluated. The film thickness can be controlled using ALD, and surface reactions can easily occur in thin films owing to the short distances between the active sites and charge carriers. In addition, unlike a powder catalyst, the bilayer photocatalyst is fixed in the solution; therefore, it does not make the solution turbid or disturb the light penetration. Diethylzinc and titanium tetraisopropoxide are used as precursors for Zn and Ti, and the thin films are deposited on soda-lime glass substrates at 150 °C using H2O as the reactant gas. The photocatalytic activity and stability are evaluated through photodegradation tests using methylene blue aqueous solution. The ZnO single-substance thin film exhibits a high degradation rate, but its performance significantly decreases after three consecutive experiments. The TiO2 single-substance thin film exhibits a relatively low degradation rate, but high reusability, exhibiting characteristics opposite to that of ZnO. Therefore, a TiO2 thin film is coated on ZnO to leverage both these advantages. The thin films are heat-treated at 400 °C for 10 min after deposition in a vacuum atmosphere. The surface morphology, crystal structure, and electrical characteristics of the photocatalyst specimens are analyzed through high-resolution scanning electron microscopy, Cs-corrected scanning transmission electron microscopy, and x-ray diffraction analysis. Their photocatalytic performances under ultraviolet (UV) irradiation are measured through UV–visible spectroscopy. The heat-treated ZnO/TiO2 heterostructured thin film exhibits a photodegradation rate exceeding 80%, with little degeneration after three cycles, indicating enhanced photodegradation performance and stability.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"71 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140234467","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":"High-performance a-Ga2O3 solar-blind photodetectors by pulsed magnetron sputtering deposition","authors":"Difei Xue, Peiwen Lv, Kai Peng, Qiang Hu, Chen Chen","doi":"10.1116/6.0003442","DOIUrl":"https://doi.org/10.1116/6.0003442","url":null,"abstract":"Solar-blind photodetectors (SBPDs) based on the ultrawide-bandgap semiconductor Ga2O3 have gained attention due to their potential applications in both military and civilian domains. As technology advances, photodetectors are being improved to achieve better energy efficiency, smaller size, and better performance. Solar-blind photodetectors based on a metal-semiconductor-metal structure of amorphous gallium oxide (a-Ga2O3) films were fabricated by pulsed magnetron sputtering deposition (PSD). The photodetector based on amorphous gallium oxide has a responsivity of 71.52 A/W, a fast rising and falling response time of less than 200 ms, a photo-to-dark current ratio (PDCR) of 6.52 × 104, and an external quantum efficiency of 34 526.62%. PSD-prepared gallium oxide SBPDs demonstrate a cost-effective room temperature method for growing gallium oxide and show the advantages of growing gallium oxide.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"7 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140242962","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":"Radiation damage effects on electronic and optical properties of β-Ga2O3 from first-principles","authors":"Xiaoning Zhang, Xi Liang, Xing Li, Yuan Li, Jia-yue Yang, Linhua Liu","doi":"10.1116/6.0003430","DOIUrl":"https://doi.org/10.1116/6.0003430","url":null,"abstract":"β-Ga2O3 with an ultra-wide bandgap demonstrates great promise in applications of space missions as power electronics and solar-blind photodetector. Unraveling the radiation damage effects on its material properties is of crucial importance, especially for improving the radiation tolerance of Ga2O3-based devices. Herein, we evaluate the formation energy of gallium and oxygen vacancy defects and comprehensively investigate their influence on the electronic and optical properties of β-Ga2O3 using first-principles calculations. Ga vacancies act as deep acceptors and produce p-type defects in β-Ga2O3, while the defective Ga2O3 with O vacancies exhibits the n-type characteristics. A semimetal characteristic is observed in the defective Ga2O3 with Ga vacancies, and an apparent optical absorption peak in the infrared spectral range emerges. Moreover, the self-compensation effect emerges when β-Ga2O3 contains both Ga vacancies and O vacancies, leading to the reduced absorption peak. The doping effect on the defect formation energy of β-Ga2O3 is also investigated, and Ga vacancies are found to be easily formed in the case of In doped β-Ga2O3 (InGa2O3) compared to the undoped β-Ga2O3, while O vacancies are much harder to form. This work provides insights into how gallium and oxygen vacancy defects alter electronic and optical properties of β-Ga2O3, seeking to strengthen its radiation tolerance.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"86 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140250805","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":"Impact of Nb and Al content in arc evaporation targets on Ti1−x−yAlxNbyN coating properties","authors":"Henry Dempwolf, S. Malz, Alexander Schacht, Christian Fabry, Axel Baumann, Olaf Kessler","doi":"10.1116/6.0003409","DOIUrl":"https://doi.org/10.1116/6.0003409","url":null,"abstract":"Titanium-based physical vapor deposition (PVD) coatings, such as titanium nitride (TiN) and titanium niobium nitride (TiNbN), are common solutions for surface modifications in medical applications. Ex vivo studies of retrieved knee implants indicate the demand for increased scratch and abrasion resistance of PVD coatings in clinical applications. Based on the promising mechanical performance of titanium aluminum nitride (TiAlN) as a coating for tools, the aim of this study was to evaluate the impact of the chemical composition of titanium-based nitride coatings with aluminum (Al) and niobium (Nb). Nine titanium aluminum niobium nitride (Ti1−x−yAlxNbyN) coatings with 0.4 ≤ x < 0.7 and 0 ≤ y ≤ 0.18, as well as commercial TiN and TiNbN, were coated in an industrial scale arc PVD process, following a randomized, multifactorial response surface design. The deposition rate, the scratch resistance, and the hardness were measured following standardized protocols. The microstructure of the coating was analyzed by SEM and XRD. In addition, the surface roughness was determined by laser scanning microscopy. A quadratic regression was performed to determine the impact of the chemical composition on coating properties. Experimental results and regression analyses revealed the significant impact of the chemical composition of Ti1−x−yAlxNbyN on the coating microstructure, mechanics, and morphology. Scratch resistance for initial crack formation and cohesive failure could be increased decisively, compared to TiN.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"38 S24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140250883","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":"Robust ultrablack film deposited on large-curvature magnesium alloy by atomic layer deposition","authors":"Jianfei Jin, Lin Lv, Lu Yan, Ying Li, Yunzhen Cao","doi":"10.1116/6.0003305","DOIUrl":"https://doi.org/10.1116/6.0003305","url":null,"abstract":"A broadband absorber composed of a TiAlC/SiO2 film stack prepared by atomic layer deposition was presented, which could be uniformly coated on magnesium alloys with large curvature, achieving an average absorption as high as 99.4% within the wavelength range from 400 to 1000 nm. An Al2O3/TiO2 interlayer was deposited on magnesium alloys prior to the deposition of ultrablack films, which effectively prevented corrosion of magnesium caused by Al3+ and Cl− by-products in the TiAlC film. With the presence of this interlayer, the ultrablack film on the surface of the magnesium alloy exhibited good adhesion and abrasion resistance. Furthermore, after undergoing damp heat and thermal cycling tests, the absorptions of the ultrablack film-coated magnesium alloys remained at 99.1% and 99.0%, respectively, which indicated that the film is promising for application in precision optics under harsh environmental conditions.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"34 S15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140251047","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":"Inhibition of atomic layer deposition of TiO2 by functionalizing silicon surface with 4-fluorophenylboronic acid","authors":"D. Silva-Quinones, John R. Mason, Robert Norden, A. Teplyakov","doi":"10.1116/6.0003316","DOIUrl":"https://doi.org/10.1116/6.0003316","url":null,"abstract":"As the size of the components in electronic devices decreases, new approaches and chemical modification schemes are needed to produce nanometer-size features with bottom-up manufacturing. Organic monolayers can be used as effective resists to block the growth of materials on non-growth substrates in area-selective deposition methods. However, choosing the appropriate surface modification requires knowledge of the corresponding chemistry and also a detailed investigation of the behavior of the functionalized surface in realistic deposition schemes. This study aims to investigate the chemistry of boronic acids that can be used to prepare such non-growth areas on elemental semiconductors. 4-Fluorophenylboronic acid is used as a model to investigate the possibility to utilize the Si(100) surface functionalized with this compound as a non-growth substrate in a titanium dioxide (TiO2) deposition scheme based on sequential doses of tetrakis(dimethylamido)titanium and water. A combination of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry allows for a better understanding of the process. The resulting surface is shown to be an effective non-growth area to TiO2 deposition when compared to currently used H-terminated silicon surfaces but to exhibit much higher stability in ambient conditions.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"20 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140254261","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":"Deposition rate and optical emissions in niobium oxide processes by reactive sputtering","authors":"João Saccoman, N. F. A. Neto, José H. D. da Silva","doi":"10.1116/6.0003255","DOIUrl":"https://doi.org/10.1116/6.0003255","url":null,"abstract":"Niobium oxide films find various applications, such as antireflective optical layers, gas sensors, and solar cells. They also show promise for emerging applications such as electrochromic and photocatalytic devices. In order to optimize the deposition of niobium oxide films by RF reactive sputtering, a detailed investigation of the plasma parameters was performed. A pure metallic target and a mixture of Ar and O2 in different proportions were used in the experiments. The deposition power was varied between 120 and 260 W, while the total pressure was kept at 0.67 Pa throughout. Deposition rates, discharge self-bias voltage, and plasma optical emissions were monitored and analyzed. Additionally, computer simulations of the process utilizing existing models were conducted and a comparative analysis with the experimental results was performed. The main findings include mapping the deposition conditions as functions of oxygen flow rate. The flow ranges in which the deposition regime changes from metallic to oxygen contaminated target conditions were identified. The narrow O2 flow range associated with the regime changes was characterized by significant changes in the self-bias voltages and plasma emissions from oxygen, argon, and niobium. The observations evidence the importance of the detailed analysis of the deposition process to get the desired stoichiometry and optimized film properties.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"110 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140251751","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":"Interlayer registry effects on the electronic and piezoelectric properties of transition metal dichalcogenide bilayers","authors":"S. Likith, Geoff L. Brennecka, Cristian V. Ciobanu","doi":"10.1116/6.0003264","DOIUrl":"https://doi.org/10.1116/6.0003264","url":null,"abstract":"Transition metal dichalcogenides (TMDC) are currently drawing significant interest from the scientific community as 2D materials that have intrinsically semiconducting bandgaps. One additional advantage of TMDCs for discovering and developing materials with novel electronic, electromechanical, or optoelectronic properties is that both layer composition and registry can be readily tailored. To understand how such tailoring can expand the range of properties, here we used density functional theory calculations to determine the electronic structure and piezoelectric properties of bilayer TMDC heterostructures based on MoX2 and WX2, where X can be S, Se, or Te. For identical layers with no misorientation with respect to one another, we find that the registry of the two layers can change the bandgap type (direct vs indirect), as well as its value (by ≈0.25 eV). We report similar conclusions for bilayer heterostructures in which the composition of the two layers is different. Interlayer registry also has a pronounced effect on piezoelectric properties as the piezoelectric coefficients of the two layers either nearly cancel each other or add up to yield enhanced values for the associated TMDC bilayer heterostructures. These results may serve as a guide for enhancing electronic and piezoelectric properties by stacking TMDC layers.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"37 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140259501","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":"Electrochemically structured tantalum surfaces via anodization for core-shell nanostructures: Optimization and characterization of Zn-ZnO nanoparticle deposition using magnetron sputtering","authors":"Levent Kara, S. Calderon, S. Carvalho","doi":"10.1116/6.0003266","DOIUrl":"https://doi.org/10.1116/6.0003266","url":null,"abstract":"This study explores the electrochemical anodization of tantalum surfaces to create nanostructured substrates for the deposition of Zn-ZnO nanoparticles (NPs) through magnetron sputtering. The anodization process, conducted at different potentials (25 V and 50 V), resulted in tantalum surfaces with distinct dimple structures. The formation of these nano-level dimples is attributed to the dynamic equilibrium between the continuous formation and dissolution of the anodic TaOx layer. The dimple diameter is observed to increase with applied potential, correlating with the dissolution rate of the anodic oxide. The NP deposition parameters were studied in two steps. First, the effect of the deposition conditions on the nanoparticle size and distribution was evaluated and optimized on silicon substrates. Second, the conditions that resulted in the optimum size and distribution of the nanoparticles were utilized in tantalum substrates and evaluated to which extent these conditions were reproduced onto the anodized Ta substrate. Comparisons of Zn-ZnO nanoparticle depositions on silicon and tantalum substrates reveal similar island growth trends, with differences in nanoparticle size and distribution attributed to substrate properties. Further investigation involves anodized tantalum substrates with varying dimple sizes, and deposition conditions are adjusted with bias voltage, pressure, and deposition time to control nanoparticle characteristics. Characterization of the Zn-ZnO nanoparticles deposited on anodized tantalum surfaces is performed using scanning electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The resulting core-shell structures are confirmed through structural analysis, revealing a core of hexagonal close-packed Zn and a shell of ZnO. The study demonstrates the influence of substrate properties and deposition conditions on the morphology and composition of Zn-ZnO nanoparticles, providing insights for applications in nanoelectronics and catalysis.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"80 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140077326","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":"Nucleation of highly uniform AlN thin films by high volume batch ALD on 200 mm platform","authors":"Partha Mukhopadhyay, Ivan Fletcher, Zuriel Caribe Couvertier, Brent Schwab, John Gumpher, W. Schoenfeld, Jon Kretzschmar, Anton deVilliers, Jim Fulford","doi":"10.1116/6.0003405","DOIUrl":"https://doi.org/10.1116/6.0003405","url":null,"abstract":"A highly uniform aluminum nitride thin film has been developed by thermal atomic layer deposition (ALD), which is designed to handle high volume of 200 mm wafers. A three-sigma thickness variation of <0.5 Å resulted from repeatable batch depositions of over 500 Å, while wafer-within-wafer (WinW) and wafer-to-wafer (WtoW) remained <5% by the optimized recipe in a 100+ wafer reactor. Various ALD deposition temperatures, film thicknesses, and substrate types of Si, quartz, and GaN/Si(111) templates have been examined for material and optical properties of an AlN film. A narrow temperature window of 300–350 °C was identified as the most suitable for the deposition process with 350 °C as the optimized one. Substrate-inhibited growth and nonlinearity in deposition rate have been observed for AlN which is possibly related to the available reaction sites at the time of nucleation on foreign substrate surfaces. A special set of experiments with a thorough exploration of XPS individual peaks such as Al2p, N1s, C1s, and O1s reveals negligible carbon and oxygen contamination with cent-percent Al–N bonding. An amorphous AlN film is evident on Si by cross-sectional TEM while a trace of polycrystalline film on GaN templates with smooth heterointerfaces to AlGaN/GaN structures. The optical bandgap is estimated to be 5.8 eV from the transmittance experiment. An in-depth refractive-index investigation shows high-density AlN by TEL Alpha-8SEiTM batch ALD which also exhibits excellent uniformity over composition and thickness with run-to-run (RtoR), WtoW, and WinW uniformity under 0.5%, highlighting the reliability and precision of the process while having high throughput.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science &amp; Technology A","volume":"142 34","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140078280","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}