Importance of Nanocrystallites in a-Si:H Passivation Layer in Improving The Performance of Silicon Heterojunction Solar Cells

Correlation between surface passivation of crystalline silicon and the microstructure of silicon passivation layer has been investigated. Based on the optical constants determined by Spectroscopic Ellipsometry measurements, effective medium approximations has been employed to simulate the microstructure of silicon thin film with the mixed phase, including amorphous structure and spherical or ellipsoidal crystallites. A key factor f(c), describes the volume fraction of nanocrystallites in the amorphous network, has a significant role to improve the fill factor of silicon heterojunction solar cells. Moreover, the cell performance can be improved by the increasing material density of intrinsic silicon interface layer.