Preparation and Characterization of p-Type Copper Gallium Oxide (CuGaO2) Thin Films by Dual Sputtering Using Cu and Ga2O3 Targets

Abstract

For the first time, this research focuses on the deposition and characterization of radio frequency (RF) sputtered p-type CuGaO2 thin films using the dual-target sputtering technique with Cu and Ga2O3 targets. The sputtering power to the Cu target was varied from 5 W to 50 W while having the Ga2O3 sputtering power constant at 200 W. The deposited films were subsequently annealed at two different annealing temperatures of 800 °C and 900 °C in N2 ambiance. The effects of variation in Cu sputtering power and annealing temperature on structural, optical, and electrical properties of CuGaO2 thin films are reported in this work. Single-phase CuGaO2 was confirmed in films deposited with Cu sputtering power of 25 W by XRD analysis. XPS analysis revealed a near stoichiometric composition ratio of Cu:Ga in films deposited with Cu sputtering power of 25 W. The optical studies were performed in 200 nm–800 nm wavelengths on all the post-deposition annealed films. The optical transmission was found to decrease with an increase in Cu sputtering power. The optical bandgap was found to be between 3.3 and 4.6 eV. Single-phase CuGaO2 film was p-type with a resistivity of 60 Ω-cm. This resistivity value is one of the lowest ever reported values identified from CuGaO2 thin films.