Schottky barrier study of ion implantation damage in GaAs

Abstract

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 °C and significant degradation occurs at a higher temperature of 700 °C. Carrier compensation and suppression of donorlike antisite defects AsGa have been found in a Ga-rich region resulting from either ion bombardment or high-temperature annealing.