Longitudinal‐Optical‐Phonon effects on excitons in GaAs‐Ga_1−xAl_xAs quantum well

Abstract

We have calculated the effects of the longitudinal optical phonons on the exciton binding energy in a quantum well, comisting of a single slab of GaAs sandwiched between two semi-infinite slabs of Gal-,AI,As, as a function of the size of the GaAs well. We have found that the correction due to the bulk-like LO-phonon effects on the exciton binding energy is quite larger than that due to thc confined LO-phonon effects and that these effects on the binding energy of the light-hole exciton are larger than those of the hcavy-hole exciton. Our results are compared with recent experimental data, and good agreement has been found.

Effect of Electron(Hole)-Confined Longitudinal Optical Phonon Interactions on the Exciton Binding Energy in Quantum-Well Wires

“…In the case of N 2 20 (L % 100 A Ê ), N 1 40 we have E HH 16 meV and E LH 14 meV, in the limit N 1 3 I (200) they become E HH 14 meV and E LH 12 meV, which certainly overestimates the excitonic binding energy. This limit is in good agreement with that we obtained for the finite well with the same width (L 100 A Ê ) E HH 10 meV and E LH 11 meV [8].…”

“…One can note that these effects are very weak. For large width the approach of confined phonons is not valid and the bulk-like approach takes place with a large correction as shown for quantum wells [8], in this case the wave function should be modified.…”

“…The 2D case was formulated before in the same manner [8], changing z by r in the wave function and in the interaction Hamiltonian. But we can check the qualitative 2D limit for the exciton binding energy by comparing the result obtained by assuming a perfect confinement of the carriers in the wires.…”

“…Degani and Hipolito [4] have used the so-called bulk-phonon approximation and calculated the polaronic effects on the exciton binding energies. Recently, we have shown that the nature of the phonon (bulk-like or confined) has a different effect on the exciton binding energy in quantum wells [8]. Indeed, phonon confinement was shown by experiment [9].…”