Zero-bias Contact Resistances of Au-GaAs Scottky Barriers

Abstract

The contact resistances of gold-GaAs Schottky barriers have been measured at liquid nitrogen temperatures over the range of electron concentrations between 3.2 × 10^(18) to 2.4 × 10^(19) cm^(−3). Our theoretical treatment is based on that of Padovani and Stratton but modified to include Franz's two-band model for the imaginary wave vector of the tunneling electrons and Conley and Mahan's correction to the space-charge potential in degenerate semiconductors. The results correlate well with the theory in the 3.2 × 10^(18) to 5.6 × 10^(18) cm^(−3) range of concentrations. The theory must be extended to include the effects of fluctuating depletion width (a suggestion originally made by Bethe) to adequately explain the low contact resistances observed with the heaviest doped GaAs. This material is a degenerate and heavily compensated tin-alloy regrowth commonly used as an ohmic contact.

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