Intersublevel magnetoabsorption in the valence band ofp-typeInAs∕GaAsandGe∕Siself-assembled quantum dots

Abstract

The linear intraband (intersublevel) optical magnetoabsorption between the valence-band states in thin disk-shaped self-assembled quantum dots is studied. Strain is modeled with the continuum mechanical approach, while band mixing and the magnetic field are taken into account through the axially symmetric $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ model. The absorption spectra in $\mathrm{InAs}∕\mathrm{GaAs}$ and $\mathrm{Ge}∕\mathrm{Si}$ quantum dots are computed for the case when a magnetic field perpendicular to the dot's base is present for both $p$-polarization in the Voigt configuration and $s$-polarization in the Faraday configuration. Due to the selection rules, the transitions between the states which differ by $\ifmmode\pm\else\textpm\fi{}1$ in the total angular momentum $({F}_{z})$ dominate for $s$-polarized light, while the transitions between the states of different ${F}_{z}$ are strictly forbidden for $p$-polarization. In $\mathrm{InAs}∕\mathrm{GaAs}$ quantum dots, the magnetic field brings about a red shift of the absorption peak for $s$-polarized light, while the absorption peak for $p$-polarization is blue-shifted with respect to the zero field case, and also the absorption curves widen. In $\mathrm{Ge}∕\mathrm{Si}$, much smaller shifts of the absorption curves due to the magnetic field are found and almost no widening occurs, which is attributed to the larger number of energy levels in $\mathrm{Ge}∕\mathrm{Si}$ dots. The obtained results compare favorably with the spectroscopic measurements at zero magnetic field, especially with regard to the relative energies of the absorption peaks for $s$- and $p$-polarized light.