Influence of material design parameters on radiative recombination in GaAs doping superlattices grown by MBE

The specific luminescence process in GaAs doping superlattices arises from recombination of electrons populating low-index conduction subbands with holes in the acceptor impurity band across the indirect gap in real space. The luminescence peak energy thus directly reflects the actual value of the tunable gap for the photoexcited state of the superlattice. We have studied the tunability of the effective gap, the recombination rate, and the relative quantum efficiency on superlattice specimen of different material design parameters by means of low-temperature photoluminescence measurements. For optimized design parameters the ratio between luminescence and excitation intensity remains nearly constant over the entire tunability range of the effective gap.