Improved molecular-beam epitaxial GaAs power FET’s

Abstract

Predeposition of tin has been used as the sole dopant source to produce exponentially decreasing free-donor profiles in molecular-beam epitaxial GaAs films. The incorporation was found to be first order with respect to surface tin concentration and have an effective activation energy of −1.35±0.1 eV, which does not agree with a Schottky barrier model of incorporation. Films with such profiles were used to fabricate power FET structures which demonstrated good linearity. Source-to-drain series resistances have also been reduced by supplemental doping under the contact regions and by degenerate Ge doping of the surface regions, followed by uninterrupted growth of thin epitaxial Ge overlayers for nonalloyed tunnel-contact metallizations.