Structural and optical properties of Nb-doped β-Ga2O3 thin films deposited by RF magnetron sputtering

The intrinsic and Nb-doped β-Ga2O3 (β-Ga2O3:Nb) thin films have been deposited on the Si and quartz substrates by radio frequency magnetron technique in argon ambient. The effects of Nb doping on the structural and optical properties of Ga2O3:Nb thin films have been investigated. After Nb-doping, the crystal lattice, surface morphology, optical transmittance and optical energy gap of the β-Ga2O3 films are greatly changed. The crystal lattice of the β-Ga2O3:Nb films is augmented, the energy gap shrinks and the crystalline quality is improved. XPS spectra shows that niobium is incorporated into the oxide matrix and present in the β-Ga2O3 as Nb(Ⅳ).