Thermally stable Ir Schottky contact on AlGaN/GaN heterostructure

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 degreesC under O-2 ambient. No degradation in Schottky barrier height was observed after annealing at 500 degreesC 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. (C) 2003 American Institute of Physics.