Excitonic spectra of wide parabolic quantum wells

Abstract

Abstract. The optical properties of wide quantum wells are considered, taking into account the screened electron-hole interaction potential and parabolic confinement potentials, different for the electrons and for the holes. The role of the interaction potential which mixes the energy states according to different quantum numbers is stressed. The results obtained by our method are in agreement with the observed spectra and give the possibility to the assessment of the resonances.

Quantum confined stark effect in wide parabolic quantum wells: real density matrix approach

“…[49], [50], the direct numerical solution of the constitutive equation ( 2) is, at the moment, not available because of lack of the appropriate orthonormal basis to use in order to decrease the dimension of the 6dimensional configuration space, [51]. Therefore we use the following 3-dimensional form of the interaction potential…”

“…with parameters v, w appropriate for a given nanostructure, which enables to perform analytical calculations and reproduces the basic properties of the exciton ( [49], [50]).…”

“…As we noticed in Ref. [50], in order to account the lowest exciton state we take the single function…”

“…The behavior of the positions of the resonances is more complicated than in the narrow QWs since the lower states show a red-shift, but some higher states show a blue-shift or a zig-zag shape, and their oscillator strengths decrease. The case without the electric field was discussed in our previous paper [50]. Using the same model, we are able to include the effects of the applied field and obtain the solution in analytical form.…”

“…In most of this nanostructures the applied electric field causes a red-shift of the positions of the lowest energy states, changes in the exciton binding energy, and lowering the oscillator strengths of the resonances. Here we consider QCSE in Wide Parabolic Quantum Wells (WPQWs), of thicknesses in the growth direction of the order of a few excitonic Bohr radii of the well material (see, for example, [46]- [50] and references therein). The optical spectra of WPQWs show a large number of resonances, which are due to the transitions between confined states.…”