GaN metal–semiconductor–metal ultraviolet photodetector with IrO2 Schottky contact

Iridium oxide (IrO2) was used as the Schottky barrier materials of GaN metal–semiconductor–metal (MSM) ultraviolet photodetector. Annealing an Ir contact at 500 °C under O2 ambient, the reverse leakage current density at −5 V reduced by the four orders of magnitude, to ∼10−6 A/cm2. Simultaneously, Schottky barrier height and optical transmittance increased to 1.48 eV and 74.8% at 360 nm, respectively. The dramatic improvement originated from the formation of IrO2 by the annealing, resulting in the increase in the responsivity of the GaN MSM photodetector by one order of magnitude, in comparison with the photodetector with Pt Schottky contact.