Study on Micro-structure of Polycrystalline Silicon Surface Etched Using NaNO_3

Polycrystalline silicon surface has become a hotspot in the research of solar cells,and it is difficult to modulate the micro-structure using the common solution because the reaction speed of acid with Si is different at different crystal surfacea.In this paper,polycrystalline silicon surface was etched using the mixed solution of HF and NaNO2,and it was found that the acid solution using NaNO2 to substitute for HNO3 can optimize micro-structure of Si surface.The textured surfaces and the light trapping of the wafer were analyzed by SEM and reflection spectrum,respectively.It is found that samples give rise to many deep pit textures in a short etching time,and was good at light trapping.The reflectance is 24.1%,which is 8% lower than that obtained from the traditional solution.