Direct measurement of donor-like interface state density and energy distribution at insulator/AlGaN interface in metal/Al2O3/AlGaN/GaN by photocapacitance method

We determined the energy distribution of donor-like interface state density D-itD(E) at the Al2O3/AlGaN interface in a metal/Al2O3/AlGaN/GaN heterostructure (MISH) capacitor. In this order, we developed a point-by-point graphical method based on the measurement and simulations of the MISH photocapacitance versus ultraviolet light intensity. We found a tail-like shaped D-itD(E) strongly decreasing from the value of 5 x 10(13) to 4 x 10(12) eV(-1) cm(-2) in the energy range between 0.12 eV and 0.45 eV from the AlGaN valence band edge. (C) 2013 AIP Publishing LLC.