Comparison of Au/GaAs Schottky contact properties modified by ion bombardment damage and mechanical polishing

A comparative study of the influence of crystal damage on the electrical properties of Au/GaAs Schottky barriers has been made with 10-keV Ar ion implantation and mechanical polishing, respectively. It has been found that the same trend in barrier height modification occurs for both cases, viz., a decrease in barrier height for n-GaAs and an increase for p-GaAs. This behavior is qualitatively similar to that in Si under ion bombardment damage and has been attributed to the generation of positively charged defect states in a shallow surface layer. However, in the case of GaAs, considerable carrier compensation effects are also in evidence, giving rise to large values of series resistance and shunt conductance arising from surface leakage. These results have implications in the formation of Ohmic contacts to GaAs and in the adaptation of ion-assisted processes for GaAs surface modification.