Effect of quantum confinement on shallow acceptor transitions in δ-doped GaAs/AlAs multiple-quantum wells

We have investigated the effect of confinement on the shallow acceptor transitions in δ-doped GaAs/AlAs multiple-quantum wells with well widths ranging from 30 to 200 Å. A series of Be δ-doped GaAs/AlAs multiple-quantum wells with doping at the well center and a single epilayer of GaAs uniformly Be doped were grown by molecular beam epitaxy. Photoluminescence spectra were measured at 4, 20, 40, 80, 120, and 200 K, respectively. Two-hole transitions of the acceptor-bound exciton from the ground state, 1S3/2(Γ6), to the excited state 2S3/2(Γ6), were clearly observed. It is found that the acceptor transition energy increases with a decrease in quantum well width.