Pavel Belov
St.Petersburg State University, Russia
Title: Numerical modeling of exciton-light coupling in quantum wells
Biography
Biography: Pavel Belov
Abstract
Excitons states and exciton light-coupling in bulk semiconductors and heterostructures have been under intensive study in the last few decades. Although the exciton binding energy is relatively small in the bulk semiconductors, typically lower than the lattice vibration energy at room temperature, in the semiconductor heterostructures it can increase significantly, up to several times. The radiative properties of an exciton are characterized by the radiative decay rate, which is defined by the exciton-light coupling. In our study, the binding energy and the corresponding wave function of excitons in GaAs-based finite square quantum wells (QWs) are calculated by the numerical solution of the three-dimensional Schroedinger equation. The precise results for the lowest exciton state are obtained by the Hamiltonian discretization using the high-order finite-difference scheme. The calculations are compared with the results obtained by the standard variational approach. The exciton binding energies found by two methods coincide within 0.1 meV for the wide range of QW widths. The radiative decay rate is calculated for QWs of various widths using the exciton wave functions obtained by direct and variational methods. The radiative decay rates are confronted with the experimental data measured for high-quality GaAs/AlGaAs and InGaAs/GaAs QW heterostructures grown by molecular beam epitaxy. The measurements and results of calculations are in good agreement.