ELECTRICAL CHARACTERIZATION OF ARGON-ION SPUTTERED N-GAAS

Epitaxially grown n-type GaAs was sputtered with 0.5 keV Ar ions at doses of 10(12) and 10(15) ions/cm2. The sputter-induced defects in the GaAs were characterized using deep-level transient spectroscopy (DLTS) and the effect of these defects on the characteristics of Au Schottky barrier diodes (SBD's) fabricated on the sputtered GaAs was evaluated by current-voltage measurements. It was found that the barrier height of the SBD's decreased with ion dose from 0.97 eV for unsputtered diodes to 0.48 eV after sputtering at a dose of 10(15)/cm2. DLTS showed the presence of a multitude of sputter-induced defects at and near the GaAs surface. The defects formed during the initial stages of sputtering had the same properties as some of the primary defects introduced during electron and proton irradiation of GaAs. Isochronal annealing at temperatures of up to 350-degrees-C showed that although some defects were removed by annealing, others appeared.