An effective electrical isolation scheme by oxygen implantation effect of damage accumulation and target temperature

Two different schemes for the electrical isolation of n-type GaAs layers by oxygen implantation are compared and discussed in terms of optimum isolation and thermal stability. The effect of damage accumulation and variable implantation temperature is also investigated. A flat dopant distribution was formed by ²⁹Si⁺ implantation into SI-GaAs at multiple energies and doses. Oxygen isolation implants were performed either at 200 keV or 2 MeV with 1×10¹⁴ cm^-2 in both cases. The target temperatures during implantation were chosen to be RT and 350°C for 200 keV and RT, 100 and 200°C for 2 MeV isolation scheme. The evolution of sheet resistivity as a function of post-implant annealing temperature is examined. The 2 MeV scheme shows more or less the same trend of annealing characteristics for all three implant temperatures. The effect of implant temperature is substantial in the 200 keV case where 350°C implants show a very broad thermally stable region (>10⁷ Ω/) and this isolation persists even after annealing at 750°C. Lower damage accumulation due to enhanced dynamic annealing is also evident in this case. RT implants in the 200 keV isolation scheme do not evolve with any thermally stable annealing window but achieve an optimum isolation after annealing at 650°C and recover completely to the initial conductivity at 850°C. Comparison of both cases suggests the applications of these schemes for surface or bulk isolation of devices