Investigation Of Acid Texturing Of Poly-Si And Properties Of Silicon Nitride After Rapid Thermal Process

High efficiency and low cost are the main trend in PV industry. Poly-crystalline silicon(Poly-Si)solar cells are considered as the most promising cells in the future. So it is very important to trap the light incidence on a surface and reduce the reflectance for improving the efficiency of silicon solar cells. How to achieve good texturing process of poly-Si is the focus in poly-Si solar cells field. In this paper acid texturing of poly-Si and the effect of rapid thermal process (RTP) on properties of SiNx film were investigated.The texturing of poly-Si for solar cells with acid etching solution was investigated by means of SEM and reflection spectrum. The acid etching solution was an aqueous solution of nitric acid (HNO3) and hydrofluoric acid (HF) modified with H3PO4 and H2SO4. Results showed that the surface etched by this acid solution was distributed with uniform worm-like etched-pits and very low reflectance. HF and NaNO2 solution was firstly used to etch poly-Si,good results were obtained.The characteristics of SiNx thin films deposited by in-line PECVD after RTP were investigated by means of AFM, spectral ellipsometry, QSSPCD, reflection spectrum. After RTP, when the temperature is lower than 650℃,the thickness and refractive index of film didn't change, with the temperature raised ,the thickness decreased and refractive index increased rapidly. The lifetime of minority carrier raised when RTP temperature was lower than 500℃.when RTP temperature was high than 500℃, lifetime decreased rapidly. The reflectance of SiNx thin films is constant.