GaN MSM Ultraviolet Photodetectors with Transparent and Thermally Stable RuO[sub 2] and IrO[sub 2] Schottky Contacts

Ruthenium oxide and iridium oxide were used as the Schottky barrier materials of GaN metal-semiconductor-metal (MSM) ultraviolet photodetector. After annealing Ru and Ir contacts at 500°C under O 2 ambient, the reverse leakage current density at −5 V drastically decreased by four orders of magnitude. Furthermore, the Schottky barrier height and optical transmittance at 360 nm simultaneously increased to 1.43 eV and 71.5% for the Ru, and to 1.48 eV and 74.8% for the Ir contact. The dramatic improvements originated from the formation of thermally stable oxide phases, RuO 2 and IrO 2 , 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.