Biexciton, negative and positive trions in strongly oblate ellipsoidal quantum dot

Abstract

The biexciton, negative and positive trion states in strongly oblate ellipsoidal quantum dot are investigated in the framework of variational method and Heisenberg's uncertainty principle. Because of the oblate geometry of the quantum dot, the exciton complexes are considered as quasi-two-dimensional. The trial wave function for the biexciton and trions are constructed on the base of one-particle wave functions, which are obtained within the framework of adiabatic approximation. The dependencies of the energies and binding energies for the biexciton, negative and positive trions on the geometrical parameters of ellipsoidal quantum dot and ratio of the effective masses of the electron and hole are obtained. The recombination energies for the biexciton, negative and positive trions are considered as a function of the strongly oblate ellipsoidal quantum dot's small semiaxis. For the crossover states, it is shown that for the decreasing small semiaxis the photoluminescence emission peaks of exciton and biexciton shift to the higher energies, but the intensities remain constant. Finally, with the increase of temperature, the photoluminescence emission peaks and intensities become lower. The radiative lifetime of biexciton in ellipsoid is estimated.