Effects of Annealing on Schottky Characteristics in AlGaN/GaN HEMT with Transparent Gate Electrode

AlGaN/GaN high-electron-mobility transistors (HEMTs) with AZO and Ni/AZO transparent gate electrodes are fabricated, respectively. In addition, the Ni/Au-gated HEMTs are also produced for comparison. An excellent transparency is achieved by the AZO-gated electrodes. The effects of annealing on Schottky characteristics are investigated. Furthermore, the effects of annealing on the Schottky barrier height, and the ideality factor values of all the contacts are also evaluated. The lower gate reverse leakage current and good Schottky rectifying characteristics of all the contacts are obtained as well. Moreover, the C–V characteristics of the Ni/AZO gate electrode before and after annealing are measured by the C–V dual sweep. It is obviously observed that the interface traps and defects are significantly reduced.