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 °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.