Nitrogen concentration in ZnO films grown by magnetron sputtering in an Ar-NO plasma

Abstract

Nitrogen-doped ZnO films are grown on (0001)-oriented sapphire substrates by magnetron RF sputtering in an Ar-NO plasma at a pressure of about 10 mTorr and Ar-to-NO flow-rate ratios of 0-90. It is revealed that the nitrogen concentration in the films depends on the Ar-to-NO flow-rate ratios as well as on the nitrogen concentration in the process environment. The highest doping level of nitrogen (4.3 at %) is achieved in films deposited at a substrate temperature of 300°C and an Ar-to-NO flow-rate ratio of 90:1. These films are found to contain Zn-N bonds, but not N-O bonds.