Superior Pinch-Off Characteristics at 400 ° C in AlGaN/GaN Heterostructure Field Effect Transistors

AlGaN/GaN field effect transistors have been fabricated on SiC(0001) substrates, and the I – V characteristics in the devices have been examined from room temperature to 400°C. In addition to excellent current saturation characteristics, sufficient pinch-off characteristics have been obtained up to a temperature of 400°C for the first time, as the result of reduced crystal defects and reduced etching damage in the devices. The temperature dependence of the transconductance has been also examined. The degradation rate in the transconductance has been proved to be low above 300°C: the transconductance degraded by only 8% for a temperature increase from 350 to 400°C. Sufficient pinch-off characteristics and a relatively low degradation rate in the transconductance ensure the practical use of the devices at high temperatures.