Si-implanted GaAs metal-semiconductor field-effect transistors with InGaP surface passivation film

The authors examine a novel device structure that contains an InGaP thin film on the GaAs surface. Since InGaP has a wider bandgap than GaAs, it is expected that phi /sub B/ (Schottky barrier height) would be increased by conduction band discontinuity in the InGaP/GaAs heterojunction and that the GaAs surface would be passivated. The dependence of the phi /sub B/ of Ti/Au contacts on the InGaP film thickness is measured using Si-doped GaAs layers with a carrier concentration as high as 3*10/sup 18//cm/sup 3/. Both enhancement- and depletion-mode Si-implanted MESFETs can be easily fabricated as planar devices in the same wafer by changing the ion implantation conditions. Si-implanted InGaP/GaAs MESFETs are thus promising devices for high-speed and high-density ICs with low-noise operation.