Influence of growth temperature and post-annealing on an n-ZnO/p-GaN heterojunction diode

Abstract

We report on an n-ZnO/p-GaN heterojunction diode fabricated from zinc oxide (ZnO) films at various growth temperatures (450, 500, 550, and 600 degrees C) by RF sputtering. The films were subsequently annealed at 700 degrees C in N-2 ambient. To investigate the influence of the growth temperature of n-ZnO films, the microstructural, optical, and electrical properties were measured using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Hall measurements. The XRD pattern showed the preferred orientation along the c-axis (002) regardless of growth temperature. The PL spectra showed a dominant sharp near-band-edge (NBE) emission. Current-voltage (I-V) curves showed excellent rectification behavior. The turn-on voltage of the diode was observed to be 3.2 V for the films produced at 500 degrees C. The ideality factor of ZnO film was observed to be 1.37, which showed the best performance of the diode. (C) 2014 Elsevier B. V. All rights reserved.