The co-implantation of C and a group-II acceptor (Mg, Zn, Cd) was carried out to doses of 5 x 1014/cm2. Such co-implantation offered the possibility of maintaining III-V stoichiometry; which was beneficial with regard to C and group-II activation. The group-II implantation profiles exhibited a reduced diffusivity, due to the balance of stoichiometry which C co-implantation provided. The group-II elements, Zn and Cd, created considerable implantation damage and therefore assisted C activation by supplying the required abundance of As vacancies. The co-implantation of Mg did not, due to the low mass of this ion, create a significant amount of lattice damage at the present dose. Consequently, the implanted C remained inactive and resulted in a reduced conductivity. It was noted that this study differed from previous group-III and C co-implantation investigations because both of the co-implanted species contributed to p-type conductivity as well as helping to maintain stoichiometry.

R.Morton, S.S.Lau, D.B.Poker, P.K.Chu: Applied Physics Letters, 1996, 68[8], 1135-7