Influence of Al content on surface passivation properties of Al rich ZnO films for solar cell application

Abstract

A systematic study of hydrogen sintered aluminum rich zinc oxide (AZO) films is made from the view point of their application as surface passivation layer for silicon solar cell. AZO films of various Al and Zn molar concentration ratios (0<RAl/Zn<40%) are made and their electrical and optical properties are studied. The lowest surface recombination velocity (~10cm/s) is realized in the film with RAl/Zn≈30% as inferred from minority carrier lifetime measurements. The passivation effect of AZO layer may be attributed to presence of hydrogen whose concentration is maximum (~3.93×1022atoms/cm3) for RAl/Zn≈30%. Effect of surface passivation is manifested in the efficiency of solar cell where an improvement>4% vis-à-vis the control cell (without AZO layer) is seen after AZO layer is applied on the rear surface of the cell. © 2014 Elsevier Ltd.