Excitonic States and Photoluminescence Spectra of a Quantum Dot Molecule Exposed to the External Static Electric Field

Abstract

The influence of a static electric field on the energy levels, wave functions, and optical properties of excitons in a quantum dot molecule is analyzed. Taking into account the cylindrical symmetry of the molecule, the wave functions and excitonic energies are calculated when the external constant electric field is applied along the symmetry axis. Two dots separated by a narrow barrier are considered as one system of three‐dimensional potential wells for an electron and a hole. The six‐dimensional Schrödinger equation is transformed into the equivalent eigenvalue problem given by the system of the coupled two‐dimensional second order differential equations as the separation of the relative‐ and center‐of‐mass motion of an electron and a hole is not possible in this case. The differential equations are solved numerically using finite differences method. Having the eigenfunctions and eigenvalues, the excitonic photoluminescence intensity is calculated and analyzed. As an example, the configuration indicating on the possibility of non‐monotonic behavior of the photoluminescence intensity versus electric field is discussed. The comparison of numerical results with experimental data for the GaInAs quantum dot molecule is presented. Satisfactory agreement with the available experimental data is obtained.