An improved symmetrically-graded doped-channel heterostructure field-effect transistor

A new heterostructure field-effect transistor with an InGaAs symmetrically-graded doped-channel (SGDC) structure has been successfully investigated. The channel design demonstrated a reduced Coulomb scattering phenomenon by confining the conduction electrons away from the channel/spacer interface. Consequently, a higher current density, a higher breakdown voltage, a wider gate-voltage swing, a higher transconductance, a higher threshold voltage, and improved microwave and power characteristics were achieved by using the SGDC structure, as compared to those of conventional doped-channel devices. Besides, the AlGaAs/GaAs superlattice buffer structure was used to improve the high-temperature threshold-voltage characteristics.