Effects of notch structures on DC and RF performances of AlGaN/GaN high electron mobility transistors*

The effects of various notch structures on direct current (DC) and radio frequency (RF) performances of AlGaN/GaN high electron mobility transistors (HEMTs) are analyzed. The AlGaN/GaN HEMTs, each with a 0.8-μm gate length, 50-μm gate width, and 3-μm source–drain distance in various notch structures at the AlGaN/GaN barrier layer, are manufactured to achieve the desired DC and RF characteristics. The maximum drain current ( I ds,max ), pinch-off voltage ( V th ), maximum transconductance ( g m ), gate voltage swing (GVS), subthreshold current, gate leakage current, pulsed I – V characteristics, breakdown voltage, cut-off frequency ( f T ), and maximum oscillation frequency ( f max ) are investigated. The results show that the double-notch structure HEMT has a 30% improvement of gate voltage swing, a 42.2% improvement of breakdown voltage, and a 9% improvement of cut-off frequency compared with the conventional HEMT. The notch structure also has a good suppression of the current collapse.