Influence of Annealing Atmosphere on Microstructure and Optical Properties of ZnO Thin Films

Abstract

In this work, the ZnO films are deposited on conducting silicon chips by radio frequency magnetron sputtering. The as-deposited thin films are annealed at 800 °C in a N2, O2 and CO+N2 atmosphere for 1h, respectively. The microstructure and electrical properties of the films are comprehensively investigated. XRD studies reveal that the ZnO films have a hexagonal wurtzite structure and they are highly oriented along (002) direction. The surface roughness of ZnO films decreased after annealing, which indicates better film quality. Room temperature PL spectrum is used to investigate the band gap and native defects existing in the films. Defects of thin films for different annealing conditions are analyzed in detail and the possible mechanism of the defects emission is discussed. We suggest that annealing atmosphere of CO+N2 is the most suitable annealing conditions for obtaining ZnO thin films with better crystal quality and good luminescence performance.