Temperature dependence of photoluminescence from Mg-implanted GaAs

Photoluminescence emission characteristics from Mg-implanted GaAs are presented for the temperature range T=4.2–293 °K. The emission due to recombination of free electrons with holes bound to neutral Mg acceptors is a dominant radiative process in heavily implanted samples at temperatures T≲210 °K. Changes in the emission energies and intensities as a function of temperature lead to the determination of the binding energy of Mg as 28±2 meV. The donor-acceptor pair band involving Mg, which has a large energy shift with the change of excitation intensity, shows the lower-energy shift with an increase of temperature in the range T=4.2–50 °K. This is explained by associating deeper donor states than the hydrogenic donors to the donor-acceptor pair band. Depth dependence of the donor-acceptor pair and the free-electrons to the neutral Mg acceptor bands show a deep penetration of Mg acceptors.