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

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.