Simulations of Capacitance-Voltage-Temperature Behavior of Metal/Insulator/AlGaN and Metal/Insulator/AlGaN/GaN Structures

The effect of electronic states at insulator/AlGaN and AlGaN/GaN interfaces on capacitance-voltage (C-V) characteristics of a metal/insulator/semiconductor (MIS) capacitor with an AlGaN layer and a metal/insulator/semiconductor heterostructure (MISH) with an AlGaN/GaN heterojunction was studied theoretically taking into account extremely slow electron emission from the deep interface levels. The states at the insulator/AlGaN interface in MIS and at the AlGaN/GaN interface in MISH stretch out the C-V curves as usual, whereas the insulator/AlGaN interface states in MISH only shift the characteristics at room temperature and 300 degrees C (fixed-charge-like behavior). These effects were explained by the different positions of the Fermi level at the studied interfaces. Theoretical C-V curves were compared with experimental characteristics, which are available in the literature, measured at room and higher temperatures by the authors and others. (c) 2009 The Japan Society of Applied Physics