Characteristics of a-plane ZnO Films Grown on r-plane Sapphire Substrates by Using Pulsed Laser Deposition

Abstract

We investigated optimized growth parameters and annealing conditions for high-quality a-plane ZnO grown with a pulsed laser deposition (PLD) technique. Through measuring the FWHM of the a-plane ZnO peak in the rocking curve, the optimized conditions for growing a-plane single-crystalline ZnO were an oxygen pressure of 3 x 10(-4) Torr and a growth temperature of 500 degrees C. After the deposition process, a thermal annealing process was investigated. The surface morphology, the luminescence of the UV emission, the structural anisotropy, and the carrier mobility were improved after thermal annealing, but annealing at temperature over 700 degrees C deteriorated the quality of the a-plane ZnO films. This report presents fundamentals for the growth mode and the effects of thermal annealing on non-polar ZnO.