Defect characterization of amorphous selenium-doped Ga2O3 grown by radio frequency sputtering

Amorphous Ga2O3 thin films doped with selenium (Se) were grown by radio frequency magnetron sputtering to investigate deep-level traps via deep-level transient spectroscopy (DLTS). All samples exhibited good p+–n junction rectification, and DLTS measurements revealed distinct trap states influenced by Se incorporation and sputtering power. The undoped Ga2O3 sample exhibits two hole traps (H1: 0.61 eV, H2: 1.24 eV), while Se doping introduced an electron trap (E1: ∼0.54 eV) associated with oxygen-deficient centers (analogous to VO in β-Ga2O3 crystal lattice) as well as the hole traps (H2: 1.23–1.28 eV; and H3: 1.50 eV) associated with Ga-deficient sites (analogous to VGa in β-Ga2O3 crystal lattice). The resistivity of the samples decreases with Se doping, indicating the formation of donor-like electronic states associated with Se-induced modification of Ga-deficient local environments, analogous to SeGa antisite behavior in β-Ga2O3. These results provide insight into defect control in amorphous Ga2O3 and highlight Se doping as a viable approach for tailoring its electronic properties for oxide electronic and optoelectronic applications.