Giant enhancement of the n-type conductivity in single phase p-type ZnO:N thin films by intentionally created defect clusters and pairs

The p-type conductivity with very high transparency in visible region of electromagnetic spectrum from nitrogen doped zinc oxide (ZnO:N) thin films is reported and the origin of p-type conductivity is attributed to the formation of complex zinc interstitial-nitrogen substituted oxygen (Zn-i-No) centers. The films are irradiated using energetic ions for inducing the high density of defects/defect clusters in the lattice for increasing the conductivity of the films. A systematic change in nature of charge carriers from p- to n-type and about four orders of magnitude enhancement of n-type conductivity is observed with increase in the fluence of irradiation. The intentionally induced complex defects such as Vo/Zn-i clusters and V-Zn-V-o defects pairs are mainly ascribed to the donor defects. These induced defects also act as the compensatory defects for the p-type charge carriers at low fluences and give rise to the giant enhancement in the n-type conductivity of films at higher fluence of irradiation. (C) 2015 Elsevier Ltd. All rights reserved.