Gallium nitride photoconductive ultraviolet sensor with a sputtered transparent indium-tin-oxide ohmic contact

A gallium nitride (GaN) photoconductive ultraviolet sensor with a sputtered transparent indium-tin-oxide (ITO) contact is presented, in which a maximum photo-responsivity of 327 A/W at a bias of 5 V and a wavelength of 366 nm is achieved and attributed to good ohmic contact between ITO and n-type GaN layer. It is shown that as-deposited and annealed ITO films deposited onto n-type GaN using a radio frequency sputtering produce linear current-voltage curves that are believed to be the origin of the high photo-responsivity. In addition, annealing is shown to improve transmittance through the ITO films.