Zn-doping induced phase control mechanism of Ga2O3 thin films by spray pyrolysis deposition for application of solar-blind ultraviolet photodetector

Ga2O3 polymorphs have attracted considerable attention for optoelectronic and electronic device applications with high durability. Despite the many investigations, the crystal phase of Ga2O3 is difficult to control at low temperatures. In this study, the phase of Ga2O3 was controlled by Zn-doping at 500 °C by spray pyrolysis deposition. The pristine Ga2O3 showed the mixed α- and ε-phases, which disappeared with increasing Zn content from 0 to 60%. A single β-phase Ga2O3 thin film was formed when the Zn content was 60%. As the Zn content was increased to 120%, ZnO particles formed on the β-phase Ga2O3 surface. Therefore, the Zn dopants substitute for the Ga site and modify its coordination in the Ga2O3 matrix to form a β-phase Ga2O3. The β-Ga2O3 based solar-blind ultraviolet photodetector exhibited 1.645/0.581 s response times, a responsivity of 3.93 × 10−4 A W−1, and a detectivity of 2.65 × 1010 Jones under a bias voltage of 20 V.