Article PreviewArticle PreviewArticle PreviewThe Schottky barrier lowering in 4H-SiC interdigit Schottky-type UV photodiode is investigated in the presence of a thermally grown oxide layer on the exposed active area. Gain photocurrent is observed and correlated with the presence of the oxide and with the charge traps at the semiconductor/oxide interface. Photo-thermally stimulated current measurements evidenced that interface charge accumulation is optically promoted. Rise and fall photo-current measurements provided the time parameter of the trapping phenomenon.