Optimization of Annealing Conditions for ZnO-based Thin Films Grown Using MOCVD

Abstract

ABSTRACTIn this work, effects of thermal annealing on the structural and optical properties of ZnO thin films grown on p-Si and GaN substrates using metalorganic chemical vapor deposition (MOCVD) are investigated. Annealing at 600 °C results in optimum crystal and optical qualities of the ZnO thin films on both substrates. Smaller lattice mismatch between grown ZnO epitaxial layer on GaN substrates results in better film morphology as compared to p-Si substrates. Higher annealing temperature along with a slower thermal ramp provides better crystal quality of ZnO thin films on both substrates. Annealing ZnO thin films at 700 °C with a slower thermal ramp results in better crystal quality as is evident from a 56% reduction in the full-width at half maximum (FWHM) of the (002) peak compared to the as-grown films. The optical quality also enhances with a slower annealing rate. The determination of the optimum annealing conditions for different substrates has important implications in fabricating optimized and efficient ZnO based electronics.