RF-current de-confinement in III-V HFETs

A criterion for the carrier confinement in III-V HFETs is derived from the linear correlation between the two ratios Cgs/Cgd and gm/gds, where Cgs is the gate/source capacitance, Cgd is the gate/drain capacitance, gm is the transconductance, and gds is the output conductance. FETs of a number of distinctly different layer structures have been compared on this basis. The model finds carrier flow confinement dominated by the structural aspect ratio and the extension of the drain region. In the RF analysis no evidence for additional confinement of hot carriers by a deep-quantum-well channel configuration is found either in GaAs-based or in InP-based material systems.<>