Enhancement of Schottky barrier height on AlGaN/GaN heterostructure by oxidation annealing

Abstract

The effect of preannealing of AlGaN under an oxygen ambient on the improvement of the Schottky barrier height on an AlGaN/GaN heterostructure was studied using synchrotron radiation photoemission spectroscopy. The oxidation annealing increased the Schottky barrier height from 0.59 to 0.84 eV, and dramatically reduced the reverse leakage current. The group-III elements (Ga, Al) outdiffused to the surface to form group-III oxides during the annealing, leaving group-III vacancies behind. The surface Fermi level shifted to the energy levels of group-III vacancies, leading to the enhancement of Schottky properties of AlGaN. (C) 2003 American Institute of Physics.