Structure Parameters and Electric Field Effects on Exciton Binding Energies of CdTe/ZnTe Quantum Rings

Abstract

We study the effects of the structural parameters such as the wetting layer thickness and the size of self-assembled CdTe/ZnTe quantum rings (QRs) under an external electric field on the exciton binding energies due to Coulomb interaction between electrons and holes with a finite-element method based on the linear elasticity theory of solids and the eight-band k . p Hamiltonian. The exciton binding energies are shown to decrease linearly with increasing the outer diameter of QRs and to decrease with increasing the wetting layer thickness, agreeing with the results of the truncated quantum dots (QDs). It is shown that the isotropic probability density distribution of the electron and the hole waves is strongly affected by the static electric field and shifts in opposite directions with increasing electric field intensity, i.e., by the quantum Stark effect, similar to the case of truncated QDs. However, it is demonstrated that both the exciton binding energies with different QR heights decrease linearly but saturate to a constant value, compared to those of truncated QDs which decrease parabolically with increasing electric field intensity. (c) 2013 The Japan Society of Applied Physics