Temperature dependence of frequency dispersion in C-V characteristics of AlN/AlGaN/GaN MIS-HFET

摘要

Temperature dependence of frequency dispersion in C-V characteristics of AlN/AlGaN/GaN metal-insu- lator-semiconductor heterostructure field-effect transistors (MIS-HFETs) is reported. Applying sputtering-deposited AlN as a gate dielectric, we attained AlN/AlGaN/GaN MIS-HFETs with significant suppression of forward gate leakage currents. However, large frequency dispersion in the C-V characteristics of the device is observed owing to high-density AlN/AlGaN interface states. In order to elucidate the behavior of the interface states deteriorating the device performance, we investigated temperature dependence of the frequency dispersion in the C-V characteristics. As a result, we obtained the activation energies of electron trapping, namely the interface state energy levels, for a wide range of the gate biases. Through characterizing the activation energy modulated by the gate bias, we directly evaluated the gate-control efficiency of the device.