Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ra...Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.展开更多
The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiO_(x)/perovskite interface.In this study,a novel microstructure-control technology is ...The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiO_(x)/perovskite interface.In this study,a novel microstructure-control technology is proposed for fabrication of porous NiO_(x)films using Pluronic P123 as the structure-directing agent and acetylacetone(AcAc)as the coordination agent.The synthesized porous NiO_(x)films enhanced the hole extraction efficiency and reduced recombination defects at the NiO_(x)/perovskite interface.Consequently,without any modification,the power conversion efficiency(PCE)of the PSC with MAPbl_(3)as the absorber layer improved from 16.50%to 19.08%.Moreover,the PCE of the device composed of perovskite Cs0.05(MA_(0.15)FA_(0.85))_(0.95)Pb(I_(0.85)Br_(0.15))_(3)improved from 17.49%to 21.42%.Furthermore,the application of the fabricated porous NiO_(x)on fluorine-doped tin oxide(FTO)substrates enabled the fabrication of large-area PSCs(1.2 cm^(2))with a PCE of 19.63%.This study provides a novel strategy for improving the contact at the NiO_(x)/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.展开更多
As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties a...As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties and easy fabrication method. X-ray photoelectron spectroscopy (XPS) was used to determine the stoichiometry and composition of electroless Sb<sub>2</sub>Se<sub>3</sub> thin films using depth profile studies. The surface layers were analyzed nearly stoichiometric. But the abundant amount of antimony makes the inner layer electrically more conductive.展开更多
Spray pyrolysis method was used to deposit Lutetium Oxide (Lu<sub>2</sub>O<sub>3</sub>) thin films using lutetium (III) chloride as source material and water as oxidizer. Annealing was carried ...Spray pyrolysis method was used to deposit Lutetium Oxide (Lu<sub>2</sub>O<sub>3</sub>) thin films using lutetium (III) chloride as source material and water as oxidizer. Annealing was carried out in argon atmosphere at 450°C for 60 minutes of the films. To investigate the composition and stoichiometry of sprayed as-deposited and annealed Lu<sub>2</sub>O<sub>3</sub> thin films, depth profile studies using X-ray photoelectron spectroscopy (XPS) was done. Nearly stoichiometric was observed for both annealed and as-deposited films in inner and surface layers.展开更多
Ga<sub>2</sub>O<sub>3</sub> thin films were fabricated by spray pyrolysis method using gallium acetylacetonate as source material and water as oxidizer. The films were annealed at 450°C fo...Ga<sub>2</sub>O<sub>3</sub> thin films were fabricated by spray pyrolysis method using gallium acetylacetonate as source material and water as oxidizer. The films were annealed at 450°C for 60 minutes in argon atmosphere. X-ray photoelectron spectroscopy (XPS) depth profile studies were carried out to analyze the stoichiometry and composition of sprayed as-deposited and annealed Ga<sub>2</sub>O<sub>3</sub> thin films. Surface layers and the inner layers of as-deposited and annealed films were found nearly stoichiometric.展开更多
Sb<sub>2</sub>S<sub>3</sub> has gained tremendous research recently for thin film solar cell absorber material because of their easy synthesis, unique electrical and optical properties. The sto...Sb<sub>2</sub>S<sub>3</sub> has gained tremendous research recently for thin film solar cell absorber material because of their easy synthesis, unique electrical and optical properties. The stoichiometry and composition of electroless Sb<sub>2</sub>S<sub>3</sub> thin films were analyzed using XPS depth profile studies. The surface layers were found nearly stoichiometric. On the other hand, the inner layer was rich in antimony composition making it more conductive electrically.展开更多
Cd_(1-x)Zn_(x)S thin films were deposited by chemical bath deposition(CBD)on the glass substrate to study the influence of cadmium sulfate concentration on the structural characteristics of the thin film.The SEM resul...Cd_(1-x)Zn_(x)S thin films were deposited by chemical bath deposition(CBD)on the glass substrate to study the influence of cadmium sulfate concentration on the structural characteristics of the thin film.The SEM results show that the thin film surfaces under the cadmium sulfate concentration of 0.005 M exhibit better compactness and uniformity.The distribution diagrams of thin film elements illustrate the film growth rate changes on the trend of the increase,decrease,and increase with the increase of cadmium sulfate concentration.XRD studies exhibit the crystal structure of the film is the hexagonal phase,and there are obvious diffraction peaks and better crystallinity when the concentration is 0.005 M.Spectrophotometer test results demonstrate that the relationship between zinc content x and optical band gap value E_(g) can be expressed by the equation E_(g)(x)=0.59x^(2)+0.69x+2.43.Increasing the zinc content can increase the optical band gap,and the absorbance of the thin film can be improved by decreasing the cadmium sulfate concentration,however,all of them have good transmittance.At a concentration of 0.005 M,the thin film has good absorbance in the 300-800 nm range,80%transmittance,and band gap value of 3.24 eV,which is suitable for use as a buffer layer for solar cells.展开更多
In this study, Indium Tin Oxide (ITO) thin films were deposited by electron beam evaporation on white glass substrates with thicknesses of about 50, 100 and 170 nm. We investigated structural properties by X-ray Diffr...In this study, Indium Tin Oxide (ITO) thin films were deposited by electron beam evaporation on white glass substrates with thicknesses of about 50, 100 and 170 nm. We investigated structural properties by X-ray Diffraction (XRD) and X-ray reflectivity (XRR). The results showed that ITO thin films have a crystalline structure with a domain that increases in size with increasing thickness. For uniform electron density, as the thin film roughness increases, reflectivity curve slope also increases. Also thinner film has more fringes than thicker film. The roughness determines how quickly the reflected signal decays. XRR technique is more suitable for very thin films, approximately 20 nm and less.展开更多
TixAl1-xN films have been prepared by RF reactive magnetron sputtering. X-ray diffraction results showed that TixAl1-xN thin films in this study were hexagonal wurtzite structure with the Ti content up to 0.18. X-ray ...TixAl1-xN films have been prepared by RF reactive magnetron sputtering. X-ray diffraction results showed that TixAl1-xN thin films in this study were hexagonal wurtzite structure with the Ti content up to 0.18. X-ray photoelectron spectrocopy studies provided that the Nls core-electron spectrum of TixAl1-xN thin film brodend with increasing Ti content, and the difference of the chemical shifts for Ti2p3/2 line between TiN and TixAl1-xN th77pj in film was 0.7 eV.展开更多
Arrays of silicon micro\|tips were made by etching the p\|type (1 0 0) silicon wafers which had SiO 2 masks with alkaline solution. The density of the micro\|tips is 2×10 4 cm -2 . The Scanning Elect...Arrays of silicon micro\|tips were made by etching the p\|type (1 0 0) silicon wafers which had SiO 2 masks with alkaline solution. The density of the micro\|tips is 2×10 4 cm -2 . The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly. The CN x thin film, with the thickness of 1.27μm was deposited on the silicon micro\|tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X\|ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12.6 % and O: 17.9 %. The silicon arrays coated with CN x thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm 2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CN x thin films are likely to be good field emission cathode. The preparation and the characterization of the samples were discussed in detail.展开更多
Glancing Angle X-ray Diffraction (GAXRD) is introduced as a direct, non-destructive, surface-sensitive technique for analysis of thin films. The method was applied to polycrystalline thin films (namely, titanium oxide...Glancing Angle X-ray Diffraction (GAXRD) is introduced as a direct, non-destructive, surface-sensitive technique for analysis of thin films. The method was applied to polycrystalline thin films (namely, titanium oxide, zinc selenide, cadmium selenide and combinations thereof) obtained by electrochemical growth, in order to determine the composition of ultra-thin surface layers, to estimate film thickness, and perform depth profiling of multilayered heterostructures. The experimental data are treated on the basis of a simple absorption-diffraction model involving the glancing angle of X-ray incidence.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No.51802025)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No.2020JQ-384)。
文摘Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.
基金supported by the National Key Research and Development Program of China(grant no.2018YFA0208701)National Natural Science Foundation of China(grant no.21773308)+6 种基金Research Funds of Renmin University of China(grant nos.2017030013,201903020,and 20XNH059)Fundamental Research Funds for Central Universities(China)supported by the Solar Energy Research Institute of Singapore(SERIS)at the National University of Singapore(NUS)supported by NUS,the National Research Foundation Singapore(NRF),the Energy Market Authority of Singapore(EMA),and the Singapore Economic Development Board(EDB)the experimental support from Suzhou Fangsheng FS-300funding from Deutsche Forschungsge-meinschaft(DFG)via Germany's Excellence Strategy-EXC 2089/1-390776260(e-conversion)as well as from TUM.solar in the context of the Bavarian Collaborative Research Project Solar Technologies Go Hybrid(SoITech)the China Scholarship Council(CSC)funding
文摘The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiO_(x)/perovskite interface.In this study,a novel microstructure-control technology is proposed for fabrication of porous NiO_(x)films using Pluronic P123 as the structure-directing agent and acetylacetone(AcAc)as the coordination agent.The synthesized porous NiO_(x)films enhanced the hole extraction efficiency and reduced recombination defects at the NiO_(x)/perovskite interface.Consequently,without any modification,the power conversion efficiency(PCE)of the PSC with MAPbl_(3)as the absorber layer improved from 16.50%to 19.08%.Moreover,the PCE of the device composed of perovskite Cs0.05(MA_(0.15)FA_(0.85))_(0.95)Pb(I_(0.85)Br_(0.15))_(3)improved from 17.49%to 21.42%.Furthermore,the application of the fabricated porous NiO_(x)on fluorine-doped tin oxide(FTO)substrates enabled the fabrication of large-area PSCs(1.2 cm^(2))with a PCE of 19.63%.This study provides a novel strategy for improving the contact at the NiO_(x)/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.
文摘As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties and easy fabrication method. X-ray photoelectron spectroscopy (XPS) was used to determine the stoichiometry and composition of electroless Sb<sub>2</sub>Se<sub>3</sub> thin films using depth profile studies. The surface layers were analyzed nearly stoichiometric. But the abundant amount of antimony makes the inner layer electrically more conductive.
文摘Spray pyrolysis method was used to deposit Lutetium Oxide (Lu<sub>2</sub>O<sub>3</sub>) thin films using lutetium (III) chloride as source material and water as oxidizer. Annealing was carried out in argon atmosphere at 450°C for 60 minutes of the films. To investigate the composition and stoichiometry of sprayed as-deposited and annealed Lu<sub>2</sub>O<sub>3</sub> thin films, depth profile studies using X-ray photoelectron spectroscopy (XPS) was done. Nearly stoichiometric was observed for both annealed and as-deposited films in inner and surface layers.
文摘Ga<sub>2</sub>O<sub>3</sub> thin films were fabricated by spray pyrolysis method using gallium acetylacetonate as source material and water as oxidizer. The films were annealed at 450°C for 60 minutes in argon atmosphere. X-ray photoelectron spectroscopy (XPS) depth profile studies were carried out to analyze the stoichiometry and composition of sprayed as-deposited and annealed Ga<sub>2</sub>O<sub>3</sub> thin films. Surface layers and the inner layers of as-deposited and annealed films were found nearly stoichiometric.
文摘Sb<sub>2</sub>S<sub>3</sub> has gained tremendous research recently for thin film solar cell absorber material because of their easy synthesis, unique electrical and optical properties. The stoichiometry and composition of electroless Sb<sub>2</sub>S<sub>3</sub> thin films were analyzed using XPS depth profile studies. The surface layers were found nearly stoichiometric. On the other hand, the inner layer was rich in antimony composition making it more conductive electrically.
基金This work was supported by the Tianjin Municipal Education Commission,Horizontal subject(grant number 70304901).
文摘Cd_(1-x)Zn_(x)S thin films were deposited by chemical bath deposition(CBD)on the glass substrate to study the influence of cadmium sulfate concentration on the structural characteristics of the thin film.The SEM results show that the thin film surfaces under the cadmium sulfate concentration of 0.005 M exhibit better compactness and uniformity.The distribution diagrams of thin film elements illustrate the film growth rate changes on the trend of the increase,decrease,and increase with the increase of cadmium sulfate concentration.XRD studies exhibit the crystal structure of the film is the hexagonal phase,and there are obvious diffraction peaks and better crystallinity when the concentration is 0.005 M.Spectrophotometer test results demonstrate that the relationship between zinc content x and optical band gap value E_(g) can be expressed by the equation E_(g)(x)=0.59x^(2)+0.69x+2.43.Increasing the zinc content can increase the optical band gap,and the absorbance of the thin film can be improved by decreasing the cadmium sulfate concentration,however,all of them have good transmittance.At a concentration of 0.005 M,the thin film has good absorbance in the 300-800 nm range,80%transmittance,and band gap value of 3.24 eV,which is suitable for use as a buffer layer for solar cells.
文摘In this study, Indium Tin Oxide (ITO) thin films were deposited by electron beam evaporation on white glass substrates with thicknesses of about 50, 100 and 170 nm. We investigated structural properties by X-ray Diffraction (XRD) and X-ray reflectivity (XRR). The results showed that ITO thin films have a crystalline structure with a domain that increases in size with increasing thickness. For uniform electron density, as the thin film roughness increases, reflectivity curve slope also increases. Also thinner film has more fringes than thicker film. The roughness determines how quickly the reflected signal decays. XRR technique is more suitable for very thin films, approximately 20 nm and less.
基金This work was supported by the National Natural Science Foundation of China under grant No.10474074the Hubei Natural Science Foundation under grant No.2001ABB060.
文摘TixAl1-xN films have been prepared by RF reactive magnetron sputtering. X-ray diffraction results showed that TixAl1-xN thin films in this study were hexagonal wurtzite structure with the Ti content up to 0.18. X-ray photoelectron spectrocopy studies provided that the Nls core-electron spectrum of TixAl1-xN thin film brodend with increasing Ti content, and the difference of the chemical shifts for Ti2p3/2 line between TiN and TixAl1-xN th77pj in film was 0.7 eV.
文摘Arrays of silicon micro\|tips were made by etching the p\|type (1 0 0) silicon wafers which had SiO 2 masks with alkaline solution. The density of the micro\|tips is 2×10 4 cm -2 . The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly. The CN x thin film, with the thickness of 1.27μm was deposited on the silicon micro\|tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X\|ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12.6 % and O: 17.9 %. The silicon arrays coated with CN x thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm 2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CN x thin films are likely to be good field emission cathode. The preparation and the characterization of the samples were discussed in detail.
文摘Glancing Angle X-ray Diffraction (GAXRD) is introduced as a direct, non-destructive, surface-sensitive technique for analysis of thin films. The method was applied to polycrystalline thin films (namely, titanium oxide, zinc selenide, cadmium selenide and combinations thereof) obtained by electrochemical growth, in order to determine the composition of ultra-thin surface layers, to estimate film thickness, and perform depth profiling of multilayered heterostructures. The experimental data are treated on the basis of a simple absorption-diffraction model involving the glancing angle of X-ray incidence.
