Low interface state densities at Al2O3/GaN interfaces formed on vicinal polar and non-polar surfaces

Ni/Al2O3/GaN structures with vicinal GaN surfaces from the c- or m-plane were formed. Then, electrical interface properties of the structures were systematically investigated. It was found that interface state density (Dit) at the Al2O3/GaN interface for the c-plane is higher than that for the m-plane, and post-metallization annealing is quite effective to reduce Dit for both c- and m-planes. As a result, the low Dit value of ∼ 3 × 1010 eV−1 cm−2 was demonstrated for both planes.