THERMAL OXIDATION OF LATTICE MATCHED INALN/GAN HETEROSTRUCTURES

In this work we have investigated the thermal oxidation of thin InAlN/GaN heterostructures in their lattice matched configuration (83% Al) in oxygen atmosphere at 800 °C. TEM cross sections revealed a partially crystalline oxide with an initial oxidation rate of 0.37 nm/minute. MOS diodes fabricated using the thermal oxide as a gate dielectric showed an exponential drop in the gate leakage which scales with the square root of oxidation time indicating diffusion limited oxidation through the InAlN barrier. The effect of oxidation on the interfacial InAlN/GaN sheet charge density (NS) is correlated with a reduction of thickness for short oxidation times (up to 4 min) and an abrupt change in the surface potential for longer oxidation times.