Interband optical transitions in GaAs modulation-doped quantum wells: photoreflectance experiment and self-consistent calculations

Abstract

Photoreflectance spectra of AlGaAs/GaAs/AlGaAs wide quantum wells doped by Si up to N d = 2 × 10 18 cm −3 were investigated at room temperature. Three kinds of spectral peculiarities were observed in photoreflectance spectra: a spectral line due to the GaAs band gap (1.42 eV), short-period Frantz-Keldysh oscillations originating from the barrier band gap (1.71 eV) and lines of subbands in the quantum well. The energies of optical transitions are determined by means of the least-squares approximation of experimental data by the sum of Aspnes relations. The experimental results are in good agreement with the self-consistent subband structure calculation. It is shown that with an increase of the doping level the energies of the interband transitions in the quantum well are changed.

Photoluminescence properties of modulation-doped In x Al1–x As/In y Ga1–y As/In x Al1–x As structures with strained inas and gaas nanoinserts in the quantum well

“…The optical transition energies were estimated as the difference in the ener gies of the electron (E ei ) and hole (E hj ) levels. The probability of corresponding transitions was estimated as the squared overlap integral |M| 2 of the envelope WFs of electrons and holes [31] The symmetry of the electron and hole WFs is sig nificantly affected by band bending in the CQW region caused by the potential of the δ layer of ionized donors (Fig. 5).…”