The optical and electrical properties of Hg acceptors were systematically investigated as a function of the Hg concentration. Samples were prepared by the high-energy ion implantation of Hg+ into samples that had been prepared by using the liquid encapsulated Czochralski method. Rapid thermal annealing (950C, 3s) was carried out by using an infra-red flash lamp. Photoluminescence measurements at 2K revealed that, in addition to the well-defined conduction band to Hg acceptor transition, the Hg-related so-called g neutral acceptor bound exciton band was found to shift from the C-related g line by 0.0008eV. Also, 2 shallow emissions were found for net hole concentrations of more than 2 x 1017 and 1019/cm3, respectively. It was demonstrated that even a moderately deep acceptor Hg in GaAs, with a ground-state ionization energy of 0.052eV, could produce multiple shallow emission levels that would be attributed to acceptor-acceptor pairs.

K.Harada, B.Lo, Y.Makita, A.C.Beye, M.P.Halsall, S.Kimura, N.Kobayashi, T.Iida, T.Shima, H.Shibata, A.Obara, T.Matsumori: Applied Physics Letters, 1995, 67[19], 2845-7