Carbon in GaAs: Implantation and isolation characteristics

Carbon was implanted into GaAs at doses between 1013 and 5×1014 cm−2, either by itself or with Ga coimplantation at room temperature or 200 °C. Activation percentages as high as 40% were obtained for C+Ga implants at 5×1014 cm−2 compared to <3% for C implantation only. The peak activation occurs for an annealing temperature of 800 °C for 10 s, while above this the net activation decreases, apparently due to site switching. The C shows fairly minimal redistribution during anneals up to 1000 °C in contrast to other acceptor dopants in GaAs. The formation of highly resistive (>106 Ω/⧠) layers in C-doped (p∼2×1020 cm−3) GaAs is possible by using oxygen bombardment doses above 5×1014 cm−2. Under these conditions the evolution of the implanted layer resistivity with annealing temperature can be described by the usual trap-related compensation mechanism.