Dc and Microwave Characteristics of High Transconductance AlGaN/GaN Heterostructure Field Effect Transistors on Sic Substrates

High quality AJGaN/GaN heterostructures have been successfully deposited on both nand p-type SiC substrates. Heterostructure field effect transistors fabricated using these layers exhibited high channel current density (1.71 A/mm), well behaved pinch-off characteristics, and excellent extrinsic transconductance (Gm = 229 mS/mm). There is negligible channel current degradation up to a source to drain bias of 20 V as opposed to devices grown on sapphire substrates. The 0.25 μm gate-length devices fabricated on the heterostructures grown on p-type SiC has allowed us to extract a cutoff frequency of 53 GHz. The cutoff frequency showed little deterioration with increasing drain bias voltage. These results demonstrate for the first time the high frequency and high power operation potential of the heterostructure field effect transistors based on AlGaN grown on SiC.