Phase Evolution and Optoelectronic Properties of Ga 2 O 3 Films via MOCVD for Solar-Blind UV Detection

Abstract Monoclinic gallium oxide ( β -Ga 2 O 3 ), with its ultra-wide bandgap that enables deep ultraviolet absorption, is a promising material for solar-blind UV detection. However, its practical application is still hindered by the weak photoresponse and defect-induced surface leakage. Herein, β -Ga 2 O 3 films with high crystallinity and low oxygen vacancy density were grown on c-plane sapphire by metal-organic chemical vapor deposition (MOCVD). The optimization was achieved through a systematic investigation of Ga 2 O 3 nucleation behavior and precise control of the growth temperature. The elevated growth temperature induced a gradual phase transition of the Ga 2 O 3 films from the ε phase to the β phase. When the growth temperature exceeds 600°C, the β -Ga 2 O 3 crystal orientation remains stable. A systematic investigation was conducted into the temperature-dependent growth characteristics of β -Ga 2 O 3 films, along with a comparative analysis of their optoelectronic properties. Further research is warranted to fully understand the effects of temperature on the crystal structure, surface morphology, chemical bonding states, and oxygen vacancy concentration in β -Ga 2 O 3 films. The investigation of β -Ga 2 O 3 heteroepitaxial growth offers a guidance for the high-performance Ga 2 O 3 -based devices.