Effect of annealing atmosphere on the structural and optical properties of the Nb-doped β-Ga^sub 2^O^sub 3^ films

The 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 annealing atmosphere on the structural and optical properties of β-Ga2O3:Nb thin films have been investigated. The crystallinity of β-Ga2O3:Nb film is improved obviously after annealing. An increase in surface roughness is observed on annealed films. The bandgap from 5.19 to 5.26 eV is obtained after annealing in different atmosphere, which is larger than the 5.09 eV before annealing. Moreover, the red-shift of photoluminescence emission peak is observed after annealing, and the annealing atmosphere has an influence on the peak intensity.