Reliability of Schottky contacts on AlGaN.

We compare the performance of Pt- and Ni-based Schottky contacts on Al x Ga 1-x N (x = 0, 0.31). Pt/Au contacts on GaN present lower leakage currents than Ni/Au, although they degrade at temperatures as low as 300 °C due to Pt-Au inter-diffusion. An intermediate thin Ti layer is shown to enhance thermal stability and Schottky barrier height. Pt/Ti/Au contacts with a barrier height of (1.18 ± 0.07) eV have been obtained on GaN, increasing up to (2.0 ± 0.1) eV on Al 0.31 Ga 0.69 N. Further improvement of Schottky contacts is achieved by surface passivation with SiO 2 or Si x N y , which reduces leakage current by two orders of magnitude.