A marked effect of p-type modulation doping upon radiative recombination, in epilayers which had been grown by using the molecular beam epitaxy technique, was observed by means of photoluminescence spectroscopy. Recombination between a 2-dimensional hole gas, which was confined within doped regions, and nearby electrons gave rise to 2 asymmetrical photoluminescence bands near to the band-edge when the doping level exceeded the degenerate limit. Non-optimized growth conditions and, in particular, the involvement of ion-bombardment during growth were proved to be responsible for the quenching of the 2-dimensional hole gas-related emissions. Radiation-induced defects, with the participation of doping impurities, gave rise to both broad-band photoluminescence emissions and sharp excitonic lines.

I.A.Buyanova, W.M.Chen, A.Henry, W.X.Ni, G.V.Hansson, B.Monemar: Materials Science Forum, 1995, 196-201, 479-84