Effect of rapid thermal annealing on texture and properties of pulsed laser deposited zinc oxide thin films

A comparative study on the properties of pulsed laser deposited ZnO thin films as a function of rapid thermal annealing temperature (T-a) is presented. Grazing incidence x-ray diffraction pattern reveals that preferred orientation of the films changes from (002) to (103) as T-a varies from 500 to 800 degrees C. A clear correlation between grain morphology and texture formation is noticed. Photoluminescence spectra of all films show a strong near-band-edge ultraviolet (UV) emission and the UV emission intensity increases with T-a. Simultaneously, a weak and broad green emission centered at 505 nm corresponds to oxygen vacancies also emerged in the films annealed at T-a >= 600 degrees C. A significant hysteresis behavior is observed in current-voltage characteristics and attributed to trapping/de-trapping driven effect. It is shown that high resistance state is dominated by space charge limited currents and low resistance state is governed by both Pool-Frenkel (2-5 V) and Schottky emission (0-2 V). (C) 2013 Elsevier B.V. All rights reserved.