Effects of oxygen gas flow rates and Ga contents on structural properties of Ga-doped ZnO films prepared by ion-plating with a DC arc discharge

Structural properties of highly c-axis oriented polycrystalline Ga-doped ZnO (GZO) films prepared by ion-plating with a DC arc discharge were studied in terms of the oxygen gas flow rate (FO2) introduced into the chamber during the deposition process and the Ga2O3 content in the GZO sintered pellet. The X-ray diffraction (XRD) measurements revealed that the GZO films have the residual compressive stress along the a-axis direction (in-plane) and the tensile stress along the c-axis direction (out-of-plane). The increase in FO2 or the increase in Ga2O3 content was effective for relaxing the in-plane compressive stress induced by the so-called atomic peening effect. The positive correlation between the carrier concentration (n) and the primitive cell volume (V) would be due to the incorporation of Ga atoms substituting Zn sites (GaZns) together with the generation of n-type intrinsic defects or complex defects.