Ultrathin Native Oxide by Barrier Layer Oxidation as Gate Dielectric for AlInN/GaN MIS-HEMTs

In this paper, Aluminium Oxide (Al2O3) grown by thermal oxidation of AlInN/GaN heterostructure is investigated as a gate dielectric for metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). Thermal oxidation of the hetero structure was carried out under high pressure oxygen ambient as well as by rapid thermal oxidation with an aim to reduce the process temperature and time. Post gate annealing in forming gas ambient has also been optimized to achieve minimum gate leakage current density. Compared with the reference schottky barrier device, significant reduction in gate leakage current density has been obtained in both forward and reverse region of operation. The linear dependence of the resulting oxide thickness on square root of oxidation time signifies diffusion-limited oxidation mechanism, similar to oxidation of Silicon.