Preparation of SiNx multilayer films by mid-frequency magnetron sputtering for crystalline silicon solar cells

The purpose of this study is to design hydrogenated silicon nitride/silicon nitride/silicon oxynitride (SiNx:H/SiNx/SiOxNy) multilayer films for silicon crystalline solar cells by using mid-frequency (MF) magnetron sputtering technique. Both anti-reflection and surface passivation are taking into account. Single SiNx and SiNx/SiOxNy multilayer films were firstly deposited on textured silicon wafer for optical performance evaluation. SiNx/SiOxNy film acted as antireflective layer with minimal value of 4.03% reflectance after numerical optimization. The N composition in the SiNx film was increased and its reflectance was decreased as the increase of the flow of N2. A significant O contamination was observed in all of these coatings. Then SiNx:H film employed as passivation layer was involved into SiNx/SiOxNy films system. SiNx:H/SiNx/SiOxNy multilayer films still presented excellent optical quality with 5.43% reflectance. Solar cell with SiNx:H/SiNx/SiOxNy films exhibited 575 mV open circuit voltage, which was higher than the cell with silicon dioxide (SiO2) film (569 mV) and with SiNx/SiOxNy film (561 mV). Finally, SiNx:H/SiNx/SiOxNy films were applied in conventional industrial solar cell preliminarily and 17.32% best cell efficiency was achieved.