Effects of a monolayer on the electron-phonon scattering rates in a quantum well: Dielectric continuum versus hybrid model

• Published in: Journal of applied physics 1998-02, Vol.83 (3), p.1499-1506
• Main Authors: Bennett, C. R., Amato, M. A., Zakhleniuk, N. A., Ridley, B. K., Babiker, M.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.366857

Recent publications have suggested that a reduction in the total electron-phonon scattering rate in a quantum well can be achieved by the inclusion of a monolayer of a different material. The predictions have been based upon two distinct models: the dielectric continuum (DC) model and the hybrid model. In the DC model the symmetric phonon modes are modified upon introducing the monolayer (via the electromagnetic boundary conditions) and hence a reduction in the intrasubband electron-phonon scattering rate is expected. In the hybrid model it is the antisymmetric modes that are modified and a reduction in the intersubband scattering rate is thus expected. It is shown here, however, that when the calculations are done correctly the calculated rates are approximately the same for both models if the thickness of the monolayer is vanishingly small and the electron wave functions are assumed to be unchanged. This implies that the inclusion of a monolayer of a finite thickness in a quantum well will only have a marginal effect on the total scattering rates, even though the mode spectra are changed. Our results also serve as an additional test of the hybrid model when applied to a more complicated system than a single quantum well. Again, an agreement is found between the two models when calculating the total electron-phonon scattering rates. We emphasize, however, that unlike the DC model the hybrid model can also correctly model Raman spectra.