Thermally stable Ir Schottky contact on AlGaN/GaN heterostructure

Abstract

We report thermally stable Ir Schottky contacts on AlGaN/GaN heterostructure. The Schottky barrier height was increased from 0.68 to 1.07 eV, and the reverse leakage current dramatically decreased after annealing at 500 °C under O2 ambient. No degradation in Schottky barrier height was observed after annealing at 500 °C for 24 h. The oxidation annealing caused predominant Ga outdiffusion to the surface, leading to the shift of surface Fermi level to the energy level of Ga vacancy. This played a role in forming the Schottky contact with large barrier height and excellent thermal stability.