AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors on SiC substrates

We report on AlGaN/GaN metal-oxide-semiconductor heterostructure field-effe ct transistors (MOS-HFETs) grown over insulating 4H-SiC substrates. We demo nstrate that the dc and microwave performance of the MOS-HFETs is superior to that of conventional AlGaN/GaN HFETs, which points to the high quality o f SiO2/AlGaN heterointerface. The MOS-HFETs could operate at positive gate biases as high as +10 V that doubles the channel current as compared to con ventional AlGaN/GaN HFETs of a similar design. The gate leakage current was more than six orders of magnitude smaller than that for the conventional A lGaN/GaN HFETs. The MOS-HFETs exhibited stable operation at elevated temper atures up to 300 degrees C with excellent pinch-off characteristics. These results clearly establish the potential of using AlGaN/GaN MOS-HFET approac h for high power microwave and switching devices. (C) 2000 American Institu te of Physics. [S0003-6951(00)04635-0].