Structural and Optical Properties of ZnO Films Prepared by Using Ion Beam Deposition: Effect of Annealing

ZnO films were deposited on AlN/Si (111) substrates at 500 degrees C by using ion beam deposition. The as-deposited films were annealed for an hour in a mixture of air and oxygen gas at 700, 800, or 900 degrees C. X-ray diffraction revealed that ZnO films were grown epitaxially on the AlN/Si (111) substrates and were oriented along the c-axis. The structural properties were improved by increasing the annealing temperature. The morphology of the ZnO films was changed dramatically after thermal annealing. The optical properties of the annealed ZnO films were examined by using photoluminescence (PL). The PL exhibited near-band-edge (NBE) emission and deep-level emission. The samples annealed at higher temperatures showed strong NBE emission lines, together with longitudinal optical phonon replicas of free exciton recombination.