Optimization and performance of Al2O3/GaN metal–oxide–semiconductor structures

We investigate electrical properties of Ni/Al2O3/GaN metal–oxide–semiconductor (MOS) structures having different pre-treatment of GaN surface by O2, Ar and NH3, combined with various temperature of annealing. MOS and reference Ni/GaN Schottky contact are characterized using current–voltage and capacitance–voltage methods. MOS structures compared with the Schottky contact ones show leakage current reduction for all types of processing, from 3 to 5 orders of magnitude in reverse direct. We observed substantial influence of the pre-treatment on electrical parameters of MOS structures.