Effect of High Temperature Annealing on Conduction-Type ZnO Films Prepared by Direct-Current Magnetron Sputtering

We experimentally find that the ZnO thin films deposited by dc-magnetron sputtering have different conduction types after annealing at high temperature in different ambient. Hall measurements show that ZnO films annealed at 1100°C in N₂ and in O₂ ambient become n−type and p-type, respectively. This is due to the generation of different intrinsic defects by annealing in different ambient. X-ray photoelectron spectroscopy and photoluminescence measurements indicate that zinc interstitial becomes a main defects after annealing at 1100°C in N₂ ambient, and these defects play an important role for n−type conductivity of ZnO. While the ZnO films annealed at 1100°C in O₂ ambient, the oxygen antisite contributes ZnO films to p-type.