Suppression of drain conductance in InP-based HEMTs by eliminating hole accumulation

We have developed planar-type InP-based high-electron mobility transistors (HEMTs) that significantly suppress the frequency dispersion of drain conductance (g/sub d/) and the kink phenomena, and have examined the physical mechanisms of these phenomena. These phenomena appear to be caused by hole accumulation at the extrinsic source due to impact ionization. Our planar structure includes alloyed ohmic contacts that eliminate the hole barrier at the interface between the carrier-supply layer and the channel in the source and drain region to suppress hole accumulation. Therefore, the planar structure effectively eliminated hole accumulation at the extrinsic source, and suppressed g/sub d/ frequency dispersion to 25% and the kink phenomena to 50% compared with conventional structure HEMTs.