Heterojunction properties of ZnO:Al/p-Si prepared by rf magnetron sputtering

ZnO:Al/p-Si heterojunctions were fabricated by rf magnetron sputtering of ZnO films onto p-type (100) Si wafer substrates. The structural and electrical properties of the heterojunctions were investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. C-V results indicate an abrupt interface and a band bending of 0.35 eV in the silicon. The dark forward current density-voltage-temperature (J-V-T) characteristics were measured and analysed to determine the dominant current transport mechanism in the heterojunction. Our experiments suggest that the dark forward current is dominated by a multi-step tunneling process in the silicon space charge region, whereas the reverse current is found to be mainly due to thermal carrier generation in this region.