Ultra‐thin aluminum oxide as an interface passivation layer for ZnO/p‐Si heterojunction solar cells

In this paper, aluminum oxide (Al 2 O 3 ) grown by a self‐limiting atomic layer deposition (ALD) method is suggested as an interface passivation layer (IPL) to decrease the electrical recombination loss at the ZnO/p‐Si interface. The reverse leakage current ( I R ) of ZnO/p‐Si heterojunction diodes is reduced after inserting optimized Al 2 O 3 films between ZnO/p‐Si. From lifetime measurements, the effective recombination velocity trends consistently with the reverse saturation current ( I S ) of the devices tested. Also, from temperature‐dependent current–voltage ( I – V ) and diverse physical measurements, the I R is shown to be closely related to free carrier trapping sites (Zn i and V o ) near the half value of the difference in the work functions of Si and ZnO. Therefore, the experimental results show that the electrical recombination loss at the ZnO/p‐Si interface can be effectively reduced by inserting an optimized Al 2 O 3 IPL between the ZnO and p‐Si.