Preparation Of Vanadium Nitrate By Reactive Magnetron Sputtering And Its Application In Crystalline Silicon Solar Cells

Solar cells are the core of photovoltaic power generation technology,photoelectric conversion efficiency is the key parameter that characterizes solar cell performance.The high concentration of p+ layer is one of the basic structures of crystalline silicon solar cells.Its main role is to increase the barrier height on the back of the cell and realize the collection of carrier holes.At present,the p+ layer is usually prepared by the diffusion process of high temperature sintering of aluminum back electrode,but it is difficult to realize the production of heavy doping layer with high doping concentration and thin thickness,which will limit the improvement of cell conversion efficiency.In this paper,a vanadium nitride(VN)thin film with high work function is fabricated on the back surface of the solar cell by reactive magnetron sputtering to replace the doping process to realize the collection of carrier holes.The open circuit voltage VOC characterizes the effect of the vanadium nitride film.In this study,vanadium was used as the target,argon as sputtering gas and ammonia gas as the reaction gas.VN was prepared by reactive magnetron sputtering.The resistivity of the film measured by the Kelvin probe force microscope is greater than 5.1eV,and the film resistivity is measured at 1.45×10-3?·cm to 1.95x10-3?·cm,the experimental results show that the VN film is a material with high work function and good electrical conductivity.The effect of process parameters on the properties of the films was studied.The larger the ammonia flow rate,the smaller the sputtering power,the slower the deposition rate of the film.At this time,the surface morphology of the film is more uniform and the resistivity is lower.The deposition pressure has little effect on the performance of the film,and its resistivity is relatively low and the surface morphology is good when the pressure is 0.9Pa.The heating annealing process at 200 ? will cause the film to transition to a more stable crystalline state,which can improve the crystal structure of the material.The optimal preparation conditions were as follows:NH3 flow rate 40 seem,Ar flow rate 40 seem,deposition pressure 0.9Pa,and sputtering power 200W.Based on the optimum conditions,the vanadium nitride thin films were prepared on the crystalline silicon solar cells with p-layer and p-free layer on the back surface.The VOCof the p-layer structure sample was increased from the original 340mV to 472mV,and the VOC of the p-layer structure sample was increased from the original 253mV to 359mV.The results show that the application of VN thin film can improve VOC,and improve the photoelectric conversion efficiency of solar cells.Because of the low price of vanadium and the large reserves,it can reduce the production cost of crystalline silicon solar cells.The application of magnetron sputtering method can simplify the production process.If VN thin film is used in crystalline silicon solar cell,it has great development prospect.In this paper,the study of the electrical properties and microstructure of VN thin films has a certain experimental value for the research on the application of crystalline silicon solar cells.It has opened up a new reference for improving the structure of crystalline silicon solar cells and improving their photoelectric conversion efficiency.