A correlation between microstructures and high gate leakage current density of Schottky contacts on lattice-matched InxAl1−xN/GaN heterostructures was investigated by means of current-voltage measurements, conductive atom force microscopy, and transmission electron microscopy investigations. It was shown that the reverse-bias gate leakage current density of Ni/Au Schottky contacts on InxAl1−xN/GaN heterostructures was more than two orders of magnitude larger than that on AlxGa1−xN/GaN ones. Conductive atom force microscopic and transmission electron microscopic observations indicated that screw- and mixed-type threading dislocations were efficient leakage current channels in InxAl1−xN barrier and In segregation was formed around screw- and mixed-type threading dislocations. It was believed that In segregation around screw- and mixed-type threading dislocations reduced local Schottky barrier height to form conductive channels and led to high leakage current density of Schottky contacts on InxAl1−xN/GaN heterostructures.

High Conductive Gate Leakage Current Channels Induced by In Segregation Around Screw- and Mixed-Type Threading Dislocations in lattice-Matched InxAl1-xN/GaN Heterostructures. J.Song, F.J.Xu, X.D.Yan, F.Lin, C.C.Huang, L.P.You, T.J.Yu, X.Q.Wang, B.Shen, K.Wei, X.Y.Liu: Applied Physics Letters, 2010,

97[23], 232106