Impact of UV-ozone (UVO) treatment on optical and electrical properties of RF sputtered Ga2O3 thin films for opto-electronic application

Abstract

Ga2O3 has established to be a promising material for deep UV and UV optoelectronics and sensing applications. However, a major drawback of Ga2O3 thin film based optoelectronic devices is the existence of native point defects which can result in the creation of sub-bandgap absorption, carrier scattering centres, and leakage channels and becomes an obstruction to their efficient device applications. To overcome this high temperature annealing processes are required which not only leads to a rise in the thermal budget but also put many fabrication and technological bounds in device fabrication. Therefore, in this work we report room temperature ultraviolet-ozone (UVO) annealing as a facile and cost-effective method which can control defect states and improve the optical efficiency of Ga2O3 thin film. The Ga2O3 thin films were deposited by radio frequency (RF) sputtering technique on p-Si at room temperature. The grown films were subsequently subjected to UV-Ozone (UVO) annealing for 30, 50, 70, and 90 min at room temperature. The atomic force microscopy result shows the impacts of UV-Ozone (UVO) annealing time on the film roughness which further associated with reduced oxygen vacancies (Vo) concentration. Optimum time of UVO annealing for Ga2O3 thin films was estimated to be 50 min. Finally, the variation in current-voltage (I-V) characteristics of Ga2O3/p-Si heterojunctions are estimated to understand the effect UVO annealing on its electrical properties of RF sputtered Ga2O3 thin film.