GaAs power metal-insulator-semiconductor field effect transistor with superlattice gate insulator and superlattice buffer structure

Abstract

A new metal-insulator-semiconductor field effect transistor (MISFET) structure has been proposed in this paper. The use of an undoped GaAsAl 0.3Ga 0.7As superlattice gate “insulator” provides a much higher gate breakdown voltage (above 36V) with a very low pre-breakdown leakage current. As a result of the existence of this gate “insulator”, a higher carrier concentration can be employed in the active channel which improves the output drain current capability and transconductance. If the gate length is reduced to 1 μm, a higher transconductance up to 330 mS mm −1 can be expected. The insertion of a superlattice buffer structure between the active channel and buffer layer offers an excellent carrier confinement barrier and gives a degraded interface region smaller than 40 Å. In addition, the superlattice buffer structure can getter deep level impurities and defects from the substrate or buffer layer. In summary, the proposed MISFET structure is suitable for high power and low noise applications.