SCHOTTKY-BARRIER STUDY OF ION-IMPLANTATION DAMAGE IN GAAS

Ion bombardment damage on GaAs surface has been studied with Ar ion implantation, followed by controlled removal of the damaged GaAs surface layer by anodic oxidation/stripping prior to Schottky metallization. The electrical characteristics of subsequently fabricated Au/n-GaAs Schottky barriers display progressive recovery towards those of undamaged control samples as a function of implanted Ar dose. The recovery depth for different material/device parameters are well in excess of the projected range for 10-keV Ar ions (10.5 nm) in GaAs. Deep level transient spectroscopy measurements of the Ar-implanted samples show both suppression and enhancement of deep levels in the GaAs surface region. A Ga-rich surface region introduced by low-energy Ar implantation appears to be responsible for the modification of deep level traps. The recovery in Schottky barrier height with a postimplantation rapid thermal anneal process is very poor at temperatures below 600-degrees-C and significant degradation occurs at a higher temperature of 700-degrees-C. Carrier compensation and suppression of donorlike antisite defects As(Ga) have been found in a Ga-rich region resulting from either ion bombardment or high-temperature annealing.