Journal of Vacuum Science & Technology A最新文献

{"title":"Role of a surface hydroxyl group depending on growth temperature in atomic layer deposition of ternary oxides","authors":"Sanghun Lee, Seunggi Seo, Woo-Jae Lee, Wontae Noh, Se-Hun Kwon, Il-Kwon Oh, Hyungjun Kim","doi":"10.1116/6.0002880","DOIUrl":"https://doi.org/10.1116/6.0002880","url":null,"abstract":"Atomic layer deposition (ALD) of multicomponent materials is challenging because the growth characteristics often deviate from what is expected due to the difference in surface characteristics of heterogeneous and single materials, resulting in undesired thickness or properties. For metal oxides, the growth characteristics highly rely on the surface hydroxyl groups, which play a role as the reactive site. Thus, studying the reaction mechanism of a precursor on hydroxyl-terminated heterogeneous surfaces is important for understanding the nonideal growth of ternary oxide. Here, we investigated the correlation between hydroxyl and the growth of ALD TiSiOx depending on temperature, analyzing infrared spectra, and chemical compositions. The results show that large amounts of hydroxyl are detected in TiSiOx deposited at 100 °C, where the adsorption of H2O on Ti–O–Si bonds is favorable. It leads to higher growth per cycle (GPC) than the estimated value. In contrast, the hydroxyl disappears at 200 °C due to dehydroxylation, resulting in lower GPC. Differences in hydroxyl also influence the film density as revealed in x-ray reflection spectra, which is related to the film qualities (e.g., elastic modulus and dry etch rates). This work provides insight into how to control hydroxyl in the ALD of ternary oxides, which is susceptible to hydroxyl incorporation, leading to undesired growth characteristics.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135591671","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}

{"title":"Angle resolved x-ray photoelectron spectroscopy assessment of the structure and composition of nanofilms—including uncertainties—through the multilayer model","authors":"Alberto Herrera-Gomez, Dulce Maria Guzman-Bucio, Marisol Mayorga-Garay, Orlando Cortazar-Martinez","doi":"10.1116/6.0002981","DOIUrl":"https://doi.org/10.1116/6.0002981","url":null,"abstract":"The multilayer model (MLM) for assessing the structural and composition parameters of multilayered nanofilms from angle-resolved x-ray photoelectric spectroscopy is described in detail. It is compared with regularized back-transform (RBT) approaches such as the maximum entropy method (MEM) with Tikhonov-type regularizations. The advantages of MLM over MEM, such as the possibility of assessing confidence ranges, modeling structures beyond conformal multilayered nanofilms, and modeling abrupt interfaces, are discussed and exemplified. In contrast with MLM, the RBT methods have shortcomings such as the violation of the conservation of information and the inability to adequately address the dependence of the effective attenuation length on the material. Examples of the application of MLM to conformal films and systems with protrusions are shown. The covariance matrix method (CMM) is described and applied to assess uncertainties in structural parameters and composition under the MLM. The CMM constitutes the canonical method for assessing confidence ranges and adequately accounts for the covariance among structural (e.g., layer thicknesses) and composition parameters.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739283","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}

{"title":"Band-engineered LaFeO3–LaNiO3 thin film interfaces for electrocatalysis of water","authors":"Rajendra Paudel, Andricus R. Burton, Marcelo A. Kuroda, Byron H. Farnum, Ryan B. Comes","doi":"10.1116/6.0002987","DOIUrl":"https://doi.org/10.1116/6.0002987","url":null,"abstract":"Iron and nickel-based perovskite oxides have proven promising for the oxygen evolution reaction (OER) in alkaline environments, as their catalytic overpotentials rival precious metal catalysts when the band alignment is tuned through substitutional doping or alloying. Here, we report the engineering of band alignment in LaFeO3/LaNiO3 (LFO/LNO) heterostructures via interfacial doping that yields greatly enhanced catalytic performance. The 0.2 eV offset (VBO) between the Fermi level in metallic LNO and the valence band in semiconducting LFO that we predict using density functional theory makes LFO a p-type semiconductor, resulting in significantly lower barriers for hole transport through LFO compared to the intrinsic material. Experimental band alignment measured with in situ x-ray photoelectron spectroscopy of epitaxial LFO/LNO heterostructures confirms these predictions, producing a measured VBO of 0.3(1) eV. Furthermore, OER catalytic measurements on these samples in the alkaline solution show an increase in catalytic current density by a factor of ∼275 compared to LFO grown on n-type Nb-doped SrTiO3. These results demonstrate the power of tuning band alignments through interfacial band engineering for improved catalytic performance of oxides.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739412","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}

{"title":"Plasma-enhanced atomic layer deposition of crystalline Ga2S3 thin films","authors":"Femi Mathew, Nithin Poonkottil, Eduardo Solano, Dirk Poelman, Zeger Hens, Christophe Detavernier, Jolien Dendooven","doi":"10.1116/6.0002993","DOIUrl":"https://doi.org/10.1116/6.0002993","url":null,"abstract":"Gallium (III) sulfide is a frontrunner for many energy storage and optoelectronic applications, which demand a deposition technique that offers a high level of control over thickness, composition, and conformality. Atomic layer deposition (ALD) is a potential technique in this regard. However, the state-of-the-art ALD processes for depositing Ga2S3 often lead to films that are amorphous and nonstoichiometric, and contain significant contaminations. Herein, we present a new plasma-enhanced atomic layer deposition (PE-ALD) process using the hexakis(dimethylamido)digallium precursor and H2S plasma coreactant to deposit high-quality Ga2S3 sulfide thin films and compare it to the thermal ALD process using the same reactants. While both cases exhibit typical ALD characteristics, substantial disparity is observed in the material properties. The PE-ALD process deposits crystalline Ga2S3 sulfide thin films at a temperature as low as 125 °C with a growth per cycle of 1.71 Å/cycle. Additionally, the PE-ALD process results in smooth and stoichiometric Ga2S3 films without any detectable carbon and oxygen contamination. Grazing incidence wide-angle x-ray scattering analysis indicates that the as-deposited Ga2S3 film crystallizes in a cubic structure with a preferred orientation along the [111] direction. The Ga2S3 film exhibits a transmittance of 70% and a bandgap of 3.2 eV with a direct transition.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135695632","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}

{"title":"Ion track formation and porosity in InSb induced by swift heavy ion irradiation","authors":"Taleb Alwadi, Christian Notthoff, Shankar Dutt, Jessica Wierbik, Nahid Afrin, Alexander Kiy, Patrick Kluth","doi":"10.1116/6.0003007","DOIUrl":"https://doi.org/10.1116/6.0003007","url":null,"abstract":"Ion track formation, irradiation-induced damage (amorphization), and the formation of porosity in InSb after 185 MeV 197Au swift heavy ion irradiation are studied as a function of ion fluence and irradiation angle. Rutherford backscattering spectrometry in channeling geometry reveals an ion track radius of about 16 nm for irradiation normal to the surface and 21 nm for off-normal irradiation at 30° and 60°. Cross-sectional scanning electron microscopy shows significant porosity that increases when irradiation was performed off-normal to the surface. Off-normal irradiation shows a preferential orientation of the pores at about 45° relative to the surface normal. Moreover, when subjected to identical conditions, InSb samples demonstrate notably higher swelling compared to GaSb bulk samples.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135695963","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}

{"title":"Multielectronic and multiatomic effects in the U O4,5 x-ray absorption spectroscopy of uranium dioxide","authors":"J. G. Tobin, H. Ramanantoanina, C. Daul, S.-W. Yu","doi":"10.1116/6.0002969","DOIUrl":"https://doi.org/10.1116/6.0002969","url":null,"abstract":"In order to explain all of the spectral features observed in the U O4,5 x-ray absorption spectrum of uranium dioxide (UO2), it is necessary to include both multielectron effects and multiatomic effects. The 5d (core hole)-5f (electron) angular momentum coupling that gives rise to the giant resonance has been treated within ligand field density functional theory, and the electron scattering that generates the extended x-ray absorption fine structure has been included via the spectral simulation program FEFF: both within a UO8 fluorite cluster picture. An atomic model is insufficient to explain all of the observed spectral features.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739395","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}

{"title":"Effects of C4F8 plasma polymerization film on etching profiles in the Bosch process","authors":"Tomoyuki Nonaka, Kazuo Takahashi, Akimi Uchida, Stefan Lundgaard, Osamu Tsuji","doi":"10.1116/5.0158954","DOIUrl":"https://doi.org/10.1116/5.0158954","url":null,"abstract":"The Bosch process is a deep etching method for silicon that uses C4F8 plasma-deposited polymerized films as passivation films to protect the silicon sidewalls. This study measured the deposition rate of the passivation films and the etch rate with F-radical exposure and analyzed the chemical composition of the films. Additionally, we observed the deformation of the passivation films during the Bosch process and assessed its influence on the etch profiles. As the C4F8 flow rates increased, the deposition rates attained a local maximum, subsequently decreased to a local minimum and then increased again. The deposition rates were extremely low when the pressure exceeded 10 Pa. With the increasing C4F8 flow rates, inductively coupled plasma power, and pressure, the respective bond content varied up to 10%, and C—CFX and C—C bond contents were replaced with CF2 and CF contents, respectively. The results indicated that the chemical composition of the films did not affect the etch rates of the films, and upon exposure to F radicals, the chemical composition of all films transformed into an identical chemical composition with a higher CF2 bond content. Polymerized films with low CF2-bond content deformed with F-radical exposure, enabled the passage of F radicals, and did not serve as passivation films. In addition to high deposition rates and high F-radical resistance, the Bosch process requires passivation films with high CF2 bond content. The present findings will aid in tuning the parameters of the Bosch process and increase the productivity of silicon deep reactive-ion etching.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135831051","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}

{"title":"CuFeO2 prepared by electron cyclotron wave resonance-assisted reactive HiPIMS with two magnetrons and radio frequency magnetron sputtering","authors":"A. Písaříková, J. Olejníček, I. Venkrbcová, L. Nožka, S. Cichoň, A. Azinfar, R. Hippler, C. A. Helm, M. Mašláň, L. Machala, Z. Hubička","doi":"10.1116/6.0002902","DOIUrl":"https://doi.org/10.1116/6.0002902","url":null,"abstract":"In this study, thin films of CuFeO2 were prepared using radio frequency reactive sputtering (RF) and reactive high-power impulse magnetron sputtering combined with electron cyclotron wave resonance plasma (HiPIMS-ECWR). The plasma was characterized using an RF ion probe. Plasma density, tail electron energy, and electron temperature were extracted from the measured data. The films were deposited on fluorine-doped tin oxide-coated glass and quartz glass, with the substrates being heated during the deposition process. The final delafossite CuFeO2 structure was formed after annealing in an argon gas flow at 550–600 °C. The ideal deposition conditions were found to be with a stoichiometric ratio of Cu:Fe = 1:1, which was the optimal condition for creating the delafossite CuFeO2 structure. The measured optical bandgap of CuFeO2 was 1.4 eV. The deposited CuFeO2 films were subjected to photoelectrochemical measurements in the cathodic region to investigate their potential application in solar photocatalytic water splitting. The films showed photocatalytic activity, with a photocurrent density of around 70 μA/cm2 (under an incident light irradiation of 62 mW/cm2, AM 1.5 G). The electrochemical properties of the layers were studied using open circuit potential, linear voltammetry, and chronoamperometry. The surface morphology and chemical composition of the layers were analyzed by atomic force microscopy and energy-dispersive x-ray spectroscopy, respectively. The crystalline structure was determined using XRD and Raman spectroscopy. The results of these methods are presented and discussed in this article.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135831336","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}

{"title":"Toward decoupling the effects of kinetic and potential ion energies: Ion flux dependent structural properties of thin (V,Al)N films deposited by pulsed filtered cathodic arc","authors":"Yeliz Unutulmazsoy, Dmitry Kalanov, Kyunghwan Oh, Soheil Karimi Aghda, Jürgen W. Gerlach, Nils Braun, Frans Munnik, Andriy Lotnyk, Jochen M. Schneider, André Anders","doi":"10.1116/6.0002927","DOIUrl":"https://doi.org/10.1116/6.0002927","url":null,"abstract":"Pulsed filtered cathodic arc deposition involves formation of energetic multiply charged metal ions, which help to form dense, adherent, and macroparticle-free thin films. Ions possess not only significant kinetic energy, but also potential energy primarily due to their charge, which for cathodic arc plasmas is usually greater than one. While the effects of kinetic ion energy on the growing film are well investigated, the effects of the ions’ potential energy are less known. In the present work, we make a step toward decoupling the contributions of kinetic and potential energies of ions on thin film formation. The potential energy is changed by enhancing the ion charge states via using an external magnetic field at the plasma source. The kinetic energy is adjusted by biasing the arc source (“plasma bias”), which allows us to approximately compensate the differences in kinetic energy, while the substrate and ion energy detector remain at ground. However, application of an external magnetic field also leads to an enhancement of the ion flux and hence the desired complete decoupling of the potential and kinetic energy effects will require further steps. Charge-state-resolved energy distribution functions of ions are measured at the substrate position for different arc source configurations, and thin films are deposited using exactly those configurations. Detailed characterization of the deposited thin films is performed to reveal the correlations of changes in structure with kinetic and potential energies of multiply charged ions. It is observed that the cathode composition (Al:V ratio) strongly affects the formation of the thermodynamically stable wurtzite or the metastable cubic phase. The external magnetic field applied at the arc source is found to greatly alter the plasma and, therefore, to be the primary, easily accessible “tuning knob” to enhance film crystallinity. The effect of “atomic scale heating” provided by the ions’ kinetic and potential energies on the film crystallinity is investigated, and the possibility to deposit crystalline (V,Al)N films without substrate heating is demonstrated. This study shows an approach toward distinguishing the contributions stemming from kinetic and potential energies of ions on the film growth, however, further research is needed to assess and distinguish the additional effect of ion flux intensity (current).","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135895623","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}

{"title":"Evolution of <i>β</i>-Ga2O3 to <i> <i>γ</i> </i>-Ga2O3 solid-solution epitaxial films after high-temperature annealing","authors":"Kunyao Jiang, Jingyu Tang, Chengchao Xu, Kelly Xiao, Robert F. Davis, Lisa M. Porter","doi":"10.1116/6.0002962","DOIUrl":"https://doi.org/10.1116/6.0002962","url":null,"abstract":"Atomic resolution scanning/transmission electron microscopy (S/TEM) and energy-dispersive x-ray (EDX) analysis were used to determine the effects of annealing at 800–1000 °C in air on Ga2O3 films grown on (100) MgAl2O4 at 650 °C via metal-organic chemical vapor deposition. Annealing resulted in the diffusion of Mg and Al into the films concomitantly with the transformation of β-Ga2O3 to γ-Ga2O3 solid solutions. The minimum atomic percent of Al + Mg that corresponded with the transformation was ∼4.6 at. %. Analyses of atomic-scale STEM images and EDX profiles revealed that the Al and Mg atoms in the γ-Ga2O3 solid solutions occupied octahedral sites; whereas the Ga atoms occupied tetrahedral sites. These site preferences may account for the stabilization of the γ-Ga2O3 solid solutions.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135831334","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}