Effect of texture morphology on the surface passivation and a-Si/c-Si heterojunction solar cells

The passivation characteristic of c-Si wafer with thin a-Si:H layer plays key parameter in a-Si:H/c-Si hetero-junction (HJ) solar cells. The significance of passivation depends not only on the quality of a-Si layers but also condition of c-Si substrate surface. C-Si substrates are textured to pyramid shape for effective absorption of light using NaOH or KOH with IPA. Textured c-Si substrates are different morphology and height of pyramid according to etching time. In this study, a-Si layers were deposited on c-Si substrates having different height of pyramid by PE-CVD method. High silicon pyramid with long etching time resulted into lower reflectance to illuminated light. This surface reflectance characteristic was closely related with short-circuit current (JSC) of heterojunction solar cell while minority carrier life time (MCLT) decides open-circuit voltage (Voc) and Fill Factor (F.F). Surface texturing of c-SI surface showed effects on both optical and electrical characteristics of heterojunction solar cell.