It was found experimentally that ZnO thin films deposited by dc-magnetron sputtering exhibited differing conduction types after annealing at high temperature in different ambients. Hall measurements showed that ZnO films annealed at 1100C in N2 and in O2 ambients became n-type and p-type, respectively. This was due to the generation of different intrinsic defects by annealing in different ambients. X-ray photo-electron spectroscopy and photoluminescence measurements indicated that zinc interstitials became the main defects after annealing at 1100C in N2 ambient, and these defects played an important role in the n-type conductivity of ZnO.

Effect of High Temperature Annealing on Conduction-Type ZnO Films Prepared by Direct-Current Magnetron Sputtering. Sun, L.J., He, D.K., Xu, X.Q., Zhong, Z., Wu, X.P., Lin, B.X., Fu, Z.X.: Chinese Physics Letters, 2010, 27[12], 126802