Influence of oxygen vacancies on the photoresponse of β -Ga₂O₃/SiC n – n type heterojunctions

β -Ga₂O₃/4H-SiC n – n type heterojunctions have been fabricated by depositing high quality β -Ga₂O₃ films on c -axis orientation n -type 4H-SiC substrates using laser molecular beam expitaxy. The influences of oxygen vacancies on the junction performances are investigated. It is found that the existence of oxygen vacancies degrades the rectifying and photoresponse properties of the heterojunctions. A large rectification ratio of 1900, a high 254 nm ultraviolet photosensitivity of 6308% and a zero response of 365 nm ultraviolet have been achieved by reducing oxygen vacancies. It is supposed that the oxygen vacancies in Ga₂O₃ affect the depletion layer of the n – n junction greatly. (paper)