Samples were implanted with C, using an energy of 1MeV, to doses of between 1013 and 2 x 1015/cm2 at 80, 278 or 300C. Markedly higher electrical activation was obtained in samples which were implanted at 80K, as compared with those implanted at 278 or 300C. Redistribution of the C profile during rapid thermal annealing (700 to 950C, 10s) was found to be negligible; regardless of the implantation temperature. Similar improvements in electrical properties were also observed in samples which were implanted at 80K, to a lower energy (60keV). It was concluded that, in spite of the low mass of the C ions, reduced dynamic annealing at 80K permitted the accumulation of an abundance of As vacancies which assisted C activation as a p-type dopant.

Electrical Activation of Carbon in GaAs: Implantation Temperature Effects. I.Danilov, J.P.De Souza, A.V.Murel, M.A.A.Pudenzi: Applied Physics Letters, 2001, 78[12], 1700-2