Study on Preparation of Low Reflectivity Multicrystalline Silicon by Wet Etching

In the preparation process of multicrystalline silicon solar cells,multicrystalline silicon surface texturing is a hot research topic at all times.The surface reflectivity and morphology of the textured silicon are affected by various factors.The multicrystalline silicon wafers were etched in the mixed solution of HF,HNO 3 and H 2 O.Etching time,the volume ratios of HF and HNO 3 and the volume of H 2 O in the solution were studied.The surface reflectances of the etched multicrystalline silicon wafers were analyzed by spectrophotometer and the morphologies of the textured silicon wafers were observed by scanning electron microscopy.It was found that the volume ratios of HF,HNO 3 and H 2 O has a major impact on the morphologies of etching pits,which determine the surface reflectivity.The surface reflectivity in the range of 300 nm and 900 nm is only 20.4% when the solution volume ratio of HF,HNO 3 and H 2 O is 5 ∶1 ∶2 and the etching time is 3 min,which is resulted from the narrow and deep etching pits in the textured silicon surface,where the absorption of light is increased and the reflectivity is reduced.