Photoluminescence of the Beryllium Acceptor at the Centre of Quantum Wells
Key words: quantum confined acceptors, δ-doped, multiple quantum wells, photoluminescence
Abstract: We report photoluminescence studies of internal transitions of shallow Be acceptors in bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well width ranging from 3 to 20nm.A series of Be δ-doped GaAs/AlAs multiple-quantum wells with the doping at the well center and a single epilayer of GaAs uniformly Be doped were grown by molecular beam epitaxy.The photoluminescence spectra were measured at 4,20,40,80,and 120K,respectively.A two-hole transition of the acceptor-bound exciton from the ground state,1S3/2(Γ6),to the first-excited state,2S3/2(Γ6) ,has been clearly observed.A variational principle is presented to obtain the 2s-1s transition energies of quantum confined Be acceptors as a function of the well width under the single-band effective mass and envelop function approximations.It is found that the acceptor transition energy increases with decreasing quantum-well width,and the experimental results agree well with the theoretical calculation.