Effects of Zn Doping on Optical Properties of Polycrystalline β-Ga2O3

In this study, Zn-doped Ga2O3 polycrystalline samples were prepared by solid-phase sintering, and the effects of Zn doping on the optical properties of Ga2O3 were investigated. It is found that the introduced Zn ions disrupted the Ga-O bonds and formed ZnGa, altering the Ga-O vibration modes and causing a blue shift in the related Raman mode. From near-infrared to visible light-range was a transparent region for Zn-doped Ga2O3. The fundamental optical bandgap underwent a decrease with increasing Zn doping content, primarily due to the p-d orbital hybridization of the O 2p and Zn 3d orbitals causing an upward shift valence band maximum and band renormalization effect-induced band-tails. The recombination of electrons at donor levels (VO) and holes at acceptor levels (VGa or VO-VGa) gave rise to blue-green luminescence. Zn doping increased the concentration oxygen vacancies (VO), resulting in significant blue-green luminescence enhancement in Zn-doped Ga2O3. Additionally, Zn doping resulted in a noticeable reduction in the red luminescence of Ga2O3, which may be attributed to Zn doping suppressing nitrogen incorporation from the air during high-temperature preparation processes.