Optical and Electronic Properties of InGaAs and Nitride Quantum Dots

Abstract

Semiconductor quantum dots (QDs) attract considerable attention due to their potential for fundamental studies and device applications. Here, the electronic and optical properties of such structures are investigated for the well-established III-V and the new group-III nitride system.The influence of Coulomb correlations on the optical spectra of InGaAs QDs are studied for up to twelve excitons using a full configuration interaction approach. Characteristic features are explained using simplified Hamiltonians. Recent experiments involving charged exciton complexes are analyzed.Furthermore, properties of InN/GaN quantum dots are studied. The one-particle states are provided by a tight-binding model and the existence of an exactly degenerate p-shell is discussed. We present multi-exciton spectra and investigate the influence of built-in fields. Dark (dipole forbidden) exciton and biexciton ground states are predicted for small lens-shaped dots. For larger QDs, a level reordering can lead to a bright exciton ground state. In both cases a semi-analytic discussion provides deeper insight.The photoluminescence (PL) dynamics of an initially excited QD system is studied using a microscopic theory. The influence of correlations on the PL dynamics is investigated for different photonic environments. Our theory reveals that the lack of full correlation can lead to a non-exponential and excitation-intensity dependent decay, which is also found in recent experiments.