Abstract
Nitrogen-doped ZnSe layers on GaAs substrates have been prepared by an ion doping with nitrogen during molecular beam epitaxial growth of ZnSe in an attempt to obtain p-type crystals. The preliminary work using a simple ion source without a mass separator indicated that a considerable contamination of donor species occured, together with the doping of nitrogen acceptors. The low-temperature photoluminescence (PL) was dominated by a strong donor-acceptor pair (DAP) emission. A remarkable improvement was achieved by using high-purity nitrogen atomic or molecular ions generated by an ion gun system with an ExB mass separator. The best result obtained was with an N-doped layer exhibiting a PL spectrum dominated by a strong acceptor-bound-exciton emission I1 whose peak intensity was 40 times greater than that of the DAP emission. The optimum condition for ion doping was investigated in terms of ion energy and ion current density. A temperature dependence of the PL spectrum was also reported.