Low dark current GaN Schottky UV photodiodes using oxidised IrNi Schottky contact

Ir/Ni/Ir metallisation was employed as Schottky contacts of GaN Schottky photodiodes. After annealing at 500°C in O₂ for 1 min, the Schottky contact achieved the maximum barrier height of 1.28 eV and the minimum dark current densities of 1.8×10^-10 A/cm² at -5 V bias. The peak responsivity is 105 mA/W at zero bias and increases to 150 mA/W at -15 V bias. The detectivity was estimated as 5.8×10¹⁵ cmHz¹2/ W^-1 at zero bias.