Optimization of extremely highly p-doped In/sub 0.53/Ga/sub 0.47/As:Be contact layers grown by MBE

Abstract

The growth of extremely highly Be-doped (10/sup 19/-10/sup 20/ cm/sup -3/) InGaAs contact layers for JFET devices by molecular beam epitaxy was optimized with respect to minimizing the Be diffusion. Be diffusion coefficients were found to depend exponentially on Be concentration and strongly on the growth temperature. Hole concentrations and specific resistances of Ti-Au contacts were not influenced by the growth temperature in the investigated range of 350-500 degrees C. Fairly abrupt Be doping profiles in InGaAs were attained at growth temperatures of as low as 350 degrees C even at doping densities in the 10/sup 19/ cm/sup -3/ range. JFETs employing such an optimized layer structure exhibited very high transit frequencies of nearly 30 GHz (1- mu m gate length).<>