Structure and characteristics of ZnO:Al/n-Si heterojunctions prepared by magnetron sputtering

Abstract Aluminium-doped zinc oxide (ZnO:Al) films were deposited by RF magnetron sputtering on single-crystal n-Si substrates to form ZnO:Al/n-Si heterojunctions. The structure of the ZnO:Al films was analysed by X-ray diffraction spectroscopy and scanning electron microscopy. The structural properties of the ZnO:Al/n-Si junction were studied by transmission electron microscopy. The electrical junction properties were characterised by current–voltage (I–V) and capacitance–voltage (C–V) methods. The conductance measured shows a room-temperature turn-on voltage of 0.2–0.4 V. The ideality factor and the junction built-in potential deduced from I–V and C–V plots are 1.62 and 0.56 V at room temperature, respectively. Temperature-dependent dark forward current vs. voltage measurements suggest that trap-assisted multistep tunnelling is the dominant carrier transport mechanism in this heterojunction.