Fabrication and characterization of NiO/ZnO p-n junctions by pulsed laser deposition

Transparent and conducting ZnO and NiO films were used for fabrication of p-n junction by pulsed laser deposition. These films were characterized by X-ray diffraction (XRD), atomic force microscopy, UV-visible spectroscopy, and electrical techniques. XRD shows that ZnO films are highly orientated along the (0 0 2) direction, while NiO films have preferred orientation along the (1 1 1) direction. These films are very smooth with surface roughness of similar to 1.2 nm. The optical transmittances of ZnO and NiO films are 87% and 64%, respectively. I-V characteristics of the ZnO-NiO junction show rectification. The junction parameters such as ideality factor, barrier height, and series resistance are determined using conventional forward bias I-V characteristics, the Cheung method, and Norde's function. There is a good agreement between the diode parameters obtained from these methods. The ideality factor of similar to 4.1 and barrier height of similar to 0.33 eV are estimated using current-voltage characteristics. (C) 2008 Elsevier B.V. All rights reserved.