Research On The Optical And Electrical Properties Of A-SiO_x:H Thin Films Prepared By Using PECVD

Silicon-based thin film solar cells have many advantages: raw materials storage,mature technology,preparation of low cost,and can be produced in large area etc.,and enables the silicon-based thin film solar cell to have the wide range and huge developed space.In many types of silicon-based thin film,the hydrogenated silicon oxide?SiO_x:H?is one of the broad prospective application materials.In this paper,the a-SiO_x:H thin film were mainly studied,and in particular foucsed on the relationship between the deposition parameters and the material properties.The main content of this paper researched has the following points:1.a series of hydrogenated silicon oxide?SiO_x: H?thin films were prepared by using plasma enhanced chemical vapor deposition?PECVD?technique with different carbon dioxide/silane gas flow ratios?RC=[CO₂]/[SiH₄]=0,1,0.5,2?and different substrate temperatures of 200°C and 250°C,and high press of 220 Pa,high power density of 1W·cm-2.Raman spectroscopy and X-ray diffraction spectrum deployed to detect the microstructure;and Optical properties such as refractive index,optical band gap were calculated by using UV-VIS transmission spectrum in relation with CO₂/SiH₄ gas flow ratios;Using Fourier transform infrared?FTIR?spectrum,the bonding modes and oxygen,hydrogen content in the film were tested and analyzed;Dark conductivity ?d and activation energy Ea were measured and calculated by using temperature dependent resistance test in relationship with CO₂/SiH₄ gas flow ratios.It was found that,with the inclusion and increase of carbon dioxide and gas flow,the deposition rate increases;the films transform from crystalline into amorphous phase;At the range of 500⁷50 nm wavelength,The refractive index decrease from 3.67 to 2.65 and the optical band gaps widen from 1.52 to 2.26 eV;The microstructure parameter R* increases,it means that defect density increases and quality deteriorate;activation energy Ea increases?Fermi Energy goes up?gradually.2.a series of hydrogenated silicon oxide?SiO_x: H?thin films formation from plasma enhanced chemical vapor deposition?PECVD?system was studied.The different H₂/silane gas flow ratios were discussed.Raman spectroscopy,X-ray diffraction spectrum and ultraviolet visible light transmission?UV-VIS?spectrum were deployed to detect the microstructure and optical properties of as-prepared samples.It was found that,with the increase of H₂/SiH₄ gas flow ratios,the deposition rate decreases;the films were amorphous phase;The refractive index decreases and the optical band gaps widen from 1.78 to 2.13 eV.3.the preparation of hydrogenated amorphous silicon oxide?a-SiO_x:H?thin films by using plasma enhanced chemical vapor deposition?PECVD?technique at various doping ratios of diborane/silane?RB=[B2H6]/[SiH₄]=0%?0.75%?1.5%?4.5%?7.5%?,and different carbon dioxide/silane gas flow ratios?RC=[CO₂]/[SiH₄]=0 and 1?at a substrate temperature of 200??TS = 200??,a process pressure of 220 Pa,a hydrogen dilution ratio?RH=[H₂]/[SiH₄]=200?and a power density of 1W·cm-2.We investigated the effect of various borane doping concentration on the microstrcture,optical and electrical properties of as prepared p-type a-Si Ox:H thin films via Raman spectroscopy,X-ray diffraction spectrum,ultraviolet visible light transmission spectrum?UV-VIS?and variable temperature resistance measurement method.It was found that,with the increasing of boron doping ratios,the optical band gap decreases but the refractive index increases.The dark conductivity of doped amorphous films increases monotonously with the increasing of boron doping content,while the dark conductivity of doped a-SiO_x:H films is not only determined by the concentration of dopant but also the crystallinity and oxygen content of the films.As increasing RB,the crystallinity of doped ?c-Si:H and a-SiO_x:H films simultaneously decreases,which causes the decrease of dark conductivity.Finally,B-doped a-SiO_x:H thin films with a highest dark conductivity of 0.048?-1·cm-1 have be prepared.