Electrical Properties of Gallium‐Doped Zinc Oxide Films Prepared by RF Sputtering

Abstract

Ga‐doped polycrystalline ZnO films on glass substrates were prepared by sputtering the targets, which had been prepared by sintering disks consisting of ZnO powder and various amounts of Ga2O3, to investigate the effects of gallium doping and sputtering conditions on electrical properties. Optimizing the RF power density, argon gas pressure, and gallium content, transparent Ga‐doped ZnO films with resistivity less than 10−3Ω·cm were obtained. Electron concentrations for undoped and Ga‐doped ZnO films were on the order of 1018 and 1021/cm3, respectively. The Ga‐doped ZnO films became degenerate when the electron concentration exceeded ∼ 1019/cm3, and the optical band gap increased with increasing carrier concentration because of the increase of Fermi energy in the conduction band.