Electrical characteristics of Ar-ion sputter induced defects in epitaxially grown <i>n</i>-GaAs

Abstract

Epitaxially grown n-type GaAs was sputtered by bombarding it with Ar ions at energies of between 0.5 and 5 keV at a dose of 1013 ions/cm2. The fabrication of Au Schottky barrier contacts followed directly after the sputtering. The electrical characteristics of the the sputter induced defects were studied using deep-level transient spectroscopy (DLTS). Several defects with discrete defect levels ranging from 0.05–0.70 eV below the conduction band, as well as defects with continuously distributed energies in the conduction band, were introduced during sputtering. Concentration depth profiling revealed that whereas some defects are located very close to the interface, others were detected several microns below the interface. The depth of some of these deep lying defects increased with sputter voltage. A possible explanation of the reduction in EL2 DLTS signal previously observed after sputtering is shown to be the sputter induced barrier height lowering.