0000000000445072
AUTHOR
W. Donderowicz
Photoluminescence structure of highly excited quantum dots of type II
Abstract The photoluminescence (PL) due to decay of exciton-like e–e–h complex X– (expected to appear for higher levels of activation) in electrically defined quantum dots of type II is analyzed within the Hartree approach for Gaussian confining potential, where the existence of metastable (against far-infrared interband dipole transitions) states is predicted, due to interplay of bare confinement with Coulomb interaction between the carriers. As we will show, when three-particle complexes (e–e–h) are taken into account, three PL peaks can occur at zero magnetic field, which further split into four peaks when external magnetic field is applied, which stands in a good correspondence with the…
Gaussian quantum dots of type II in in-plane electric field
The growing interest is recently focusing on QDs of type II, which contrary to type I QDs attract electrons and repulse holes (or conversely). In such QDs an electron-hole pair (Xexciton) can still be traped due to electron-hole Coulomb attraction, resulting in significantly more complex structure of excitonic states. We consider an X exciton in QD of type II defined by electrostatic focusing in a narrow quantum well, in the presence of additional external in-plane electric field. The dependence of PL spectrum on dot size and in-plane electric field is analysed within the Hartree approach for model planar Gaussian confinement. The exciton ground state and its energy red-shift are found as a…
Far-infrared laser action from parabolic quantum dots matrix
In this paper we present results of calculations for quantum dots matrix acting as an active medium in novelty proposal of far-infrared laser. The proposal is based on the pumping laser by rapid (nonadiabatic) switching on in-plane electric field which allows us to obtain population inversion. The numerical analysis of electron-photon system kinetics was performed for various electric fields and temperatures. These calculation utilises the method of solving the Cauchy problem for infinite chain of linear differential equations. Also the contribution of dynamics of non-radiative transitions mediated by the phonons has been taken account. The obtained results indicate that by the properly cho…
Laser action in electrically driven quantum dot matrix
A lasing system based on electrically driven quantum dot matrix is proposed, where population inversion of the dot matrix is obtained by rapid (nonadiabatic) switching on of in-plane electric field as a pumping force. Numerical analysis of electron-photon system kinetics is performed for various electric fields and temperatures. For parabolic type of confinement in QDs, a convenient amplification of contribution from several levels is indicated. The relevant analysis utilises an exact solution of Cauchy problem for an infinite chain of linear differential equations.
Differences between photoluminescence spectra of type-I and type-II quantum dots
Semiconductor quantum dots which trap simultaneously electrons and holes are called quantum dots of type-I. Contrary to these structures, empty dots of type-II attract only one type of charged carriers and repel the other. Particularities of confining potential are unaccessible by any direct measurements, thus recognition of quantum dot type by indirect method is highly desired. Our proposal is to distinguish between the two types of quantum dots via a comparison of photoluminescence spectra of these structures, which differ in both cases qualitatively.