Abstract
Abstract In this thesis, microwave performance of AlGaN/GaN high electron mobility transistors on high resistive silicon (111) substrate for power applications is investigated. Gate connected field plate is used. Maximum dc current density and extrinsic maximum transconductance gm,max are 700mA/mm and 138mS/mm respectively for a gate length (LG) 0.5μm device. To improve high frequency performance, the source to drain spacing is reduced to 4μm and the gate is recessed. The current gain cutoff frequency fT of 28.11 GHz and maximum frequency of available gain fmax of 60 GHz are achieved for a 0.5μm gate length device. For power characteristics, measurements are performed in continuous-wave (CW) mode at 1.8 GHz using a load-pull system. The transistor delivers a power gain of 13dB, an output power density of 0.83W/mm, and a power-added efficiency PAE of 18.43% when biased at VDS=20V and VGS=-5V in class A operation.