Effects of oxygen implantation in GaAs

Oxygen implantation in GaAs has been studied by deep level transient spectroscopy (DLTS) and current-voltage (I-V) characterization. The effect of ion dose on material electrical properties was investigated by low dose implantation at 10¹⁰, 10¹¹ and 10¹² ions/cm² with energies of 50 and 100 keV. Post-implantation annealing was studied by rapid thermal annealing (RTA) treatment at 550°C. Both n and n⁺ GaAs substrates were used to study the influence of substrate doping. Improved I-V characteristics were observed in diodes made from all as-implanted n-GaAs samples which implies the reduction of carrier concentration. At low dose implantation to n-GaAs, no induced trap levels were detected. The carrier compensation effect was explained by free carrier trapping. Therefore, residual trap elimination and carrier removal took place. At higher dose implantation in n-GaAs, two new hole traps were detected. RTA treatment showed the above compensation effect to be cancelled at a temperature of 550°C which indicated the compensation to be caused mostly by damage-related defects. For n⁺-GaAs, a higher dose is necessary for equal carrier compensation compared with lower doped n-GaAs. Additional electron traps were found for 10¹¹ and 10¹² ions/cm² implanted in n⁺-GaAs which were damage-induced defect-related.