Radiative recombination in p-type delta-doped layers in GaAs

Thin Zn-doped GaAs layers embedded in bulk GaAs, grown by metal-organic vap or phase epitaxy, are studied by means of optical spectroscopy. The concent ration of Zn accepters varies between 2 x 10(18)/cm(3) and 2 x 10(20)/cm(3) in 4 nm doping regions. With increasing doping concentration, an optical r adiative transition appears in photoluminescence (PL) spectra below the ene rgy position of the transition between the free electrons and holes bound t o accepters in bulk GaAs. The recombination shows a strong dependence on ex citation intensity and temperature. Our results indicate that this emission is related to the transition between spatially separated electrons and hol es. The holes are located in a p-type Zn-delta-doped region, while the elec trons are located in the undoped GaAs region. The magnetic-field dependence of this emission in the PL spectrum indicates that the effective mass of t he holes involved in the optical transition is about 0.2m(0). To the best o f our knowledge, this is the first time that such recombination in p-type d elta-doped GaAs is confirmed from optical spectroscopy. [S0163-1829(99)5192 8-0].