Seokhwi Song, Eungju Kim, Kyunghoo Kim, Jangho Bae, Jinho Lee, Chang Hwa Jung, Hanjin Lim, Hyeongtag Jeon
In this study, we investigated the crystallographic and electrical properties of ZrO2 thin films prepared by an ozone-based atomic layer deposition process. Cyclopentadienyl tris(dimethylamino) zirconium [CpZr(NMe2)3] was used as the Zr precursor, and O3 was used as the reactant. ZrO2 films were produced using O3 in various concentrations from 100 to 400 g/m3. These thin films were used to fabricate metal–oxide–semiconductor capacitors, whose electrical properties were evaluated and correlated with crystallographic analysis. As the O3 concentration increased, the tetragonal phase of the ZrO2 film stabilized and the dielectric constant improved. However, the leakage current density characteristics concurrently deteriorated due to the high concentration of O3, increasing the number of grain boundaries in the ZrO2 film by increasing crystallinity. Thus, the concentration of O3 can control the number of OH groups of the ZrO2 film, affecting the device characteristics.
{"title":"Stabilization of the tetragonal phase in ZrO2 thin films according to ozone concentration using atomic layer deposition","authors":"Seokhwi Song, Eungju Kim, Kyunghoo Kim, Jangho Bae, Jinho Lee, Chang Hwa Jung, Hanjin Lim, Hyeongtag Jeon","doi":"10.1116/6.0002901","DOIUrl":"https://doi.org/10.1116/6.0002901","url":null,"abstract":"In this study, we investigated the crystallographic and electrical properties of ZrO2 thin films prepared by an ozone-based atomic layer deposition process. Cyclopentadienyl tris(dimethylamino) zirconium [CpZr(NMe2)3] was used as the Zr precursor, and O3 was used as the reactant. ZrO2 films were produced using O3 in various concentrations from 100 to 400 g/m3. These thin films were used to fabricate metal–oxide–semiconductor capacitors, whose electrical properties were evaluated and correlated with crystallographic analysis. As the O3 concentration increased, the tetragonal phase of the ZrO2 film stabilized and the dielectric constant improved. However, the leakage current density characteristics concurrently deteriorated due to the high concentration of O3, increasing the number of grain boundaries in the ZrO2 film by increasing crystallinity. Thus, the concentration of O3 can control the number of OH groups of the ZrO2 film, affecting the device characteristics.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135141344","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}
Antoine Peisert, Noureddine Adjeroud, Damien Lenoble, Guillaume Lamblin
3D-Li ion batteries are identified as one of the most promising technologies for improving portable and safe energy storage devices. One of the main remaining challenges to be tackled in that regard is the manufacture of efficient nanostructured electrode materials. In this paper, we report on the first realization of an electrochemically active cathodic LixCoyOz material grown via a thermal atomic layer deposition process based on the combination of Co(thd)2 and Li(thd) organometallic ligands and O3 as an oxidizing agent. Comprehensive characterizations comprising XPS, Raman, HIM (helium ion microscopy)-SIMS, and the first ever SEM images of a thermal-atomic layer deposition (ALD) deposited LixCoyOz material are shown and discussed as well and the very first electrochemical results to attest the electrochemical activity of the deposited material. Those results act as the first demonstration that lithiated materials and more precisely, LixCoyOz, can be grown via an advanced thermal ALD.
{"title":"LixCoyOz thin-films deposition through thermal atomic layer deposition","authors":"Antoine Peisert, Noureddine Adjeroud, Damien Lenoble, Guillaume Lamblin","doi":"10.1116/6.0002863","DOIUrl":"https://doi.org/10.1116/6.0002863","url":null,"abstract":"3D-Li ion batteries are identified as one of the most promising technologies for improving portable and safe energy storage devices. One of the main remaining challenges to be tackled in that regard is the manufacture of efficient nanostructured electrode materials. In this paper, we report on the first realization of an electrochemically active cathodic LixCoyOz material grown via a thermal atomic layer deposition process based on the combination of Co(thd)2 and Li(thd) organometallic ligands and O3 as an oxidizing agent. Comprehensive characterizations comprising XPS, Raman, HIM (helium ion microscopy)-SIMS, and the first ever SEM images of a thermal-atomic layer deposition (ALD) deposited LixCoyOz material are shown and discussed as well and the very first electrochemical results to attest the electrochemical activity of the deposited material. Those results act as the first demonstration that lithiated materials and more precisely, LixCoyOz, can be grown via an advanced thermal ALD.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"213 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135350926","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}
The principal intent of this Perspective is to review the mechanisms that are responsible for the shifts of binding energies, ΔBE, observed in x-ray photoelectron spectroscopy (XPS) measurements and so to relate the shifts to the electronic structure and the chemical bonding in the systems studied. To achieve this goal, several theoretical considerations are necessary beyond just the calculation of XPS BEs. Though briefly discussed here, we are not primarily interested in absolute values of BE or quantitation using relative intensities. Within the molecular orbital (MO) theory framework, it is shown that the analysis of orbital properties is critical for the correct interpretation of XPS. In particular, rigorous definitions are given for the initial state and final state contributions to BEs and to BE shifts, ΔBE. It is first shown how the BEs of core levels are related to the electronic structure by consideration of the BEs for a model atomic system to establish the origins and magnitudes of BE shifts. The mechanisms established for the model system are then applied to a review of XPS measurements and MO theory on a set of real examples. An important focus of the paper is to demonstrate that, in many cases, initial state mechanisms allow for a definitive interpretation of the XPS BE shifts and that an important role of theory is to provide qualitative explanations rather than quantitative agreement with XPS measurements. The mechanisms established are a guide to the interpretation of XPS measurements and consideration of these mechanisms may suggest additional calculations that would be useful. It is concluded that there is still a bright future for the coupling of ab initio MO theory with XPS measurements.
{"title":"Chemical significance of x-ray photoelectron spectroscopy binding energy shifts: A Perspective","authors":"Paul S. Bagus, Connie J. Nelin, C. R. Brundle","doi":"10.1116/6.0003081","DOIUrl":"https://doi.org/10.1116/6.0003081","url":null,"abstract":"The principal intent of this Perspective is to review the mechanisms that are responsible for the shifts of binding energies, ΔBE, observed in x-ray photoelectron spectroscopy (XPS) measurements and so to relate the shifts to the electronic structure and the chemical bonding in the systems studied. To achieve this goal, several theoretical considerations are necessary beyond just the calculation of XPS BEs. Though briefly discussed here, we are not primarily interested in absolute values of BE or quantitation using relative intensities. Within the molecular orbital (MO) theory framework, it is shown that the analysis of orbital properties is critical for the correct interpretation of XPS. In particular, rigorous definitions are given for the initial state and final state contributions to BEs and to BE shifts, ΔBE. It is first shown how the BEs of core levels are related to the electronic structure by consideration of the BEs for a model atomic system to establish the origins and magnitudes of BE shifts. The mechanisms established for the model system are then applied to a review of XPS measurements and MO theory on a set of real examples. An important focus of the paper is to demonstrate that, in many cases, initial state mechanisms allow for a definitive interpretation of the XPS BE shifts and that an important role of theory is to provide qualitative explanations rather than quantitative agreement with XPS measurements. The mechanisms established are a guide to the interpretation of XPS measurements and consideration of these mechanisms may suggest additional calculations that would be useful. It is concluded that there is still a bright future for the coupling of ab initio MO theory with XPS measurements.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135350759","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}
Molecular dynamics simulations were performed to examine the amine formation in carbon-based polymer films deposited by plasma-enhanced chemical vapor deposition (PECVD) with methane (CH4) and nitrogen (N2) gases. In the simulations, the interactions between the deposited film surface and incident precursors were examined, where nitrogen species were assumed to be supplied only as amino radicals (NH2) such that the amount of primary amine (−NH2) could be maximized in the deposited film. Carbon was supplied as CH2 or CH3 radicals as well as CH2+ or CH3+ ions with an ion kinetic energy up to 100 eV, as typical in such PECVD experiments. It has been found that, even under such “ideal” conditions for the maximum primary-amine content, hydrogen (H) atoms of incident NH2 radicals tend to be transferred to surrounding C atoms in the polymerization process, leaving a relatively small amount of primary amine (the concentration ratio of primary amino groups NH2 to nitrogen atoms N ∼10%) in the deposited polymer films. The simulation results indicate that an increase of NH2 radicals in the gas phase of PECVD hardly increases the primary-amine content in the deposited films and, therefore, the primary-amine content may not depend strongly on the plasma conditions as long as a sufficient amount of nitrogen and hydrogen is supplied during the plasma polymerization process. The primary-amine content predicted by the simulations was found to be consistent with earlier experimental observations.
{"title":"Molecular dynamics simulation of amine formation in plasma-enhanced chemical vapor deposition with hydrocarbon and amino radicals","authors":"Anjar Anggraini Harumningtyas, Tomoko Ito, Michiro Isobe, Lenka Zajíčková, Satoshi Hamaguchi","doi":"10.1116/6.0002978","DOIUrl":"https://doi.org/10.1116/6.0002978","url":null,"abstract":"Molecular dynamics simulations were performed to examine the amine formation in carbon-based polymer films deposited by plasma-enhanced chemical vapor deposition (PECVD) with methane (CH4) and nitrogen (N2) gases. In the simulations, the interactions between the deposited film surface and incident precursors were examined, where nitrogen species were assumed to be supplied only as amino radicals (NH2) such that the amount of primary amine (−NH2) could be maximized in the deposited film. Carbon was supplied as CH2 or CH3 radicals as well as CH2+ or CH3+ ions with an ion kinetic energy up to 100 eV, as typical in such PECVD experiments. It has been found that, even under such “ideal” conditions for the maximum primary-amine content, hydrogen (H) atoms of incident NH2 radicals tend to be transferred to surrounding C atoms in the polymerization process, leaving a relatively small amount of primary amine (the concentration ratio of primary amino groups NH2 to nitrogen atoms N ∼10%) in the deposited polymer films. The simulation results indicate that an increase of NH2 radicals in the gas phase of PECVD hardly increases the primary-amine content in the deposited films and, therefore, the primary-amine content may not depend strongly on the plasma conditions as long as a sufficient amount of nitrogen and hydrogen is supplied during the plasma polymerization process. The primary-amine content predicted by the simulations was found to be consistent with earlier experimental observations.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135351961","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}
Vladyslav Rogoz, Oleksandr Pshyk, Bartosz Wicher, Justinas Palisaitis, Jun Lu, Daniel Primetzhofer, Ivan Petrov, Lars Hultman, Grzegorz Greczynski
Synthesis of high-entropy sublattice nitride (HESN) coatings by magnetron sputtering is typically done using custom-made alloyed targets with specific elemental compositions. This approach is expensive, requires long delivery times, and offers very limited flexibility to adjust the film composition. Here, we demonstrate a new method to grow HESN films, which relies on elemental targets arranged in the multicathode configuration with substrates rotating during deposition. TiVNbMoWN films are grown at a temperature of ∼520 °С using Ti, V, Nb, and Mo targets operating in the direct current magnetron sputtering mode, while the W target, operated by high power impulse magnetron sputtering (HiPIMS), provides a source of heavy ions. The energy of the metal ions EW+ is controlled in the range from 80 to 620 eV by varying the amplitude of the substrate bias pulses Vs, synchronized with the metal-ion-rich phase of HiPIMS pulses. We demonstrate that W+ irradiation provides dynamic recoil mixing of the film-forming components in the near-surface atomic layers. For EW+ ≥ 320 eV the multilayer formation phenomena, inherent for this deposition geometry, are suppressed and, hence, compositionally uniform HESN films are obtained, as confirmed by the microstructural and elemental analysis.
{"title":"High-mass metal ion irradiation enables growth of high-entropy sublattice nitride thin films from elemental targets","authors":"Vladyslav Rogoz, Oleksandr Pshyk, Bartosz Wicher, Justinas Palisaitis, Jun Lu, Daniel Primetzhofer, Ivan Petrov, Lars Hultman, Grzegorz Greczynski","doi":"10.1116/6.0003065","DOIUrl":"https://doi.org/10.1116/6.0003065","url":null,"abstract":"Synthesis of high-entropy sublattice nitride (HESN) coatings by magnetron sputtering is typically done using custom-made alloyed targets with specific elemental compositions. This approach is expensive, requires long delivery times, and offers very limited flexibility to adjust the film composition. Here, we demonstrate a new method to grow HESN films, which relies on elemental targets arranged in the multicathode configuration with substrates rotating during deposition. TiVNbMoWN films are grown at a temperature of ∼520 °С using Ti, V, Nb, and Mo targets operating in the direct current magnetron sputtering mode, while the W target, operated by high power impulse magnetron sputtering (HiPIMS), provides a source of heavy ions. The energy of the metal ions EW+ is controlled in the range from 80 to 620 eV by varying the amplitude of the substrate bias pulses Vs, synchronized with the metal-ion-rich phase of HiPIMS pulses. We demonstrate that W+ irradiation provides dynamic recoil mixing of the film-forming components in the near-surface atomic layers. For EW+ ≥ 320 eV the multilayer formation phenomena, inherent for this deposition geometry, are suppressed and, hence, compositionally uniform HESN films are obtained, as confirmed by the microstructural and elemental analysis.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135481364","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}
In this study, boro-tellurite glasses with a composition of 75TeO2–25B2O3 (mol. %) (TB) were synthesized using a traditional melt-quenching method. The glasses were subsequently deposited as thin films using the thermionic vacuum arc system, and a subset of the samples underwent treatment with a low-pressure cold oxygen plasma system, resulting in the formation of the “TBO (boro-tellurite treated by oxygen plasma)” thin films. The structural and morphological properties of the TB and TBO thin films were characterized using x-ray diffraction analysis, x-ray photoelectron spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, and atomic force microscopy. The optical properties of the thin film samples were evaluated using ultraviolet–visible spectrophotometry in the range of 300–800 nm. The resistivity of the thin films was measured using the four-probe Van der Pauw method. It was found that the TB thin films had an amorphous structure with some crystalline formations, whereas the TBO thin films were similar to the bulk boro-tellurite glasses described in the literature, with no detectable crystalline formations. Both TB and TBO thin films exhibited homogenous and amorphous surfaces. Furthermore, the electronic structure of the thin films has changed after oxygen plasma treatment.
{"title":"Oxygen plasma treatment of TeO2—B2O3 (boro-tellurite) thin films","authors":"Uğur Demirkol, Çağrı Durmuş, Tamer Akan","doi":"10.1116/6.0002879","DOIUrl":"https://doi.org/10.1116/6.0002879","url":null,"abstract":"In this study, boro-tellurite glasses with a composition of 75TeO2–25B2O3 (mol. %) (TB) were synthesized using a traditional melt-quenching method. The glasses were subsequently deposited as thin films using the thermionic vacuum arc system, and a subset of the samples underwent treatment with a low-pressure cold oxygen plasma system, resulting in the formation of the “TBO (boro-tellurite treated by oxygen plasma)” thin films. The structural and morphological properties of the TB and TBO thin films were characterized using x-ray diffraction analysis, x-ray photoelectron spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, and atomic force microscopy. The optical properties of the thin film samples were evaluated using ultraviolet–visible spectrophotometry in the range of 300–800 nm. The resistivity of the thin films was measured using the four-probe Van der Pauw method. It was found that the TB thin films had an amorphous structure with some crystalline formations, whereas the TBO thin films were similar to the bulk boro-tellurite glasses described in the literature, with no detectable crystalline formations. Both TB and TBO thin films exhibited homogenous and amorphous surfaces. Furthermore, the electronic structure of the thin films has changed after oxygen plasma treatment.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"3 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":"135592775","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}
Magnesium alloy, which draws attention with its lightness and high specific strength, is frequently preferred due to its advantages. However, it is necessary to improve the wear and corrosion properties in order to develop the areas of use in the automotive, aircraft, and space industries. For this purpose, after the surface preparation of the main material WE43 Mg alloy, ZnO and ZrO2 coatings were made and characterized in this study. The surface morphology and structural and chemical properties of the samples were investigated using profilometry, contact angle tests, scanning electron microscopy, and x-ray diffraction. Corrosion tests have been carried out. In order to determine the wear performance of the samples, the wear-related volume losses were measured and the friction coefficients were compared. Layers with 2–6 μm coating thickness were obtained homogeneously on the polished and sandblasted sample surfaces. It was determined that the coating layers grew in the form of columns and did not contain capillary cracks. As a result of the study, it was observed that the ZnO-coated samples had the highest wear and corrosion resistance, and the wear and corrosion resistance of the coatings and magnesium alloy substrates improved.
{"title":"Wear and corrosion resistance of zinc-oxide and zirconium-oxide coated WE43 magnesium alloy","authors":"Canser Gül, Hülya Durmuş, Sevda Albayrak, Nilay Çömez","doi":"10.1116/6.0002894","DOIUrl":"https://doi.org/10.1116/6.0002894","url":null,"abstract":"Magnesium alloy, which draws attention with its lightness and high specific strength, is frequently preferred due to its advantages. However, it is necessary to improve the wear and corrosion properties in order to develop the areas of use in the automotive, aircraft, and space industries. For this purpose, after the surface preparation of the main material WE43 Mg alloy, ZnO and ZrO2 coatings were made and characterized in this study. The surface morphology and structural and chemical properties of the samples were investigated using profilometry, contact angle tests, scanning electron microscopy, and x-ray diffraction. Corrosion tests have been carried out. In order to determine the wear performance of the samples, the wear-related volume losses were measured and the friction coefficients were compared. Layers with 2–6 μm coating thickness were obtained homogeneously on the polished and sandblasted sample surfaces. It was determined that the coating layers grew in the form of columns and did not contain capillary cracks. As a result of the study, it was observed that the ZnO-coated samples had the highest wear and corrosion resistance, and the wear and corrosion resistance of the coatings and magnesium alloy substrates improved.","PeriodicalId":17490,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"55 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":"135590513","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}
Sanghun Lee, Seunggi Seo, Woo-Jae Lee, Wontae Noh, Se-Hun Kwon, Il-Kwon Oh, Hyungjun Kim
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.
{"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}
Alberto Herrera-Gomez, Dulce Maria Guzman-Bucio, Marisol Mayorga-Garay, Orlando Cortazar-Martinez
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.
{"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}
Rajendra Paudel, Andricus R. Burton, Marcelo A. Kuroda, Byron H. Farnum, Ryan B. Comes
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.
{"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}
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