Novel silicon surface passivation by Al sub(2)O sub(3)/ZnO/Al sub(2)O sub(3) films deposited by thermal atomic layer deposition

In this paper, a novel Al sub(2)O sub(3)/ZnO/Al sub(2)O sub(3) stack is proposed as the silicon passivation layer for c-Si solar cell application. Recently, the Al sub(2)O sub(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 sub(Zn), O sub(i), and O sub(Zn)) formation determined by the room-temperature photoluminescence (RTPL) analysis. The effect of ZnO IL is investigated using Al sub(2)O sub(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 sub(2)O sub(3)/ZnO/Al sub(2)O sub(3) stack.