Novel silicon surface passivation by Al_2O_3/ZnO/Al_2O_3 films deposited by thermal atomic layer deposition

摘要

In this paper, a novel Al_2O_3/ZnO/Al_2O_3 stack is proposed as the silicon passivation layer for c-Si solar cell application. Recently, the Al_2O_3 film has been proved to be effective for passivating the p-type c-Si surface by forming the negative fixed oxide charge. It is confirmed by this experiment that the amount of negative fixed oxide charge can be controlled by inserting a ZnO interlayer (IL), which is explained by acceptor-like defect (V_(Zn), O_i, and O_(Zn)) formation determined by the room-temperature photoluminescence (RTPL) analysis. The effect of ZnO IL is investigated using Al_2O_3 bottom layers of various thicknesses by electrical and physical analyses. The effective lifetime measurement shows that the electronic recombination losses at the silicon surface are reduced effectively by optimizing the Al_2O_3/ZnO/Al_2O_3 stack.