Temperature characteristics of high-current UWBG enhancement and depletion mode AlGaN-channel MOSHFETs.

We present the temperature-dependent electrical characteristics of high-current depletion (D-mode) and barrier-recessed enhancement-mode (E-mode) ultrawide bandgap (UWBG) AlxGa1−xN channel insulated gate heterojunction field-effect transistors fabricated on the same wafer. The key motivation is the higher Baliga figure of merit for devices with the UWBG AlGaN channel and their strong potential for use in high-power, high-temperature harsh environmental applications. Over a temperature range of 125 °C, the VTH shifted in the opposite direction for D- and E-mode devices with a rate of +13.5 mV/K and −23 mV/K, respectively, giving an overall shift of +1.7 V and −2.9 V. This was attributed to changes in the fixed and trapped charge densities in the dielectric and at the dielectric–AlGaN barrier interface. A single deep sub-bandgap trap level was sufficient to explain the threshold shifts in both devices. The effective channel mobility in the E-mode devices was argued to be limited by charge scattering, arising from the same charges introduced during barrier recessing that shifted VTH. [ABSTRACT FROM AUTHOR]