Electronic and Optical Properties of Type II Quantum Ring GaAs/AlxGa1−xAs in Applied Lateral Electric Field

Abstract

A theoretical study of the effect of applying a lateral electric field on type I and type II GaAs/AlGaAs quantum rings with different Al concentrations in the barrier is presented. The effect on the quantum states of the carriers was investigated using the approximation of the effective mass. It’s shown that the electric field has a great effect on the wavefunction and the energy of the carriers. The transition point of the quantum ring from type I to type II was found with increasing electric field strength. For electric fields less than 4.75 x 10-4 V/cm, the quantum ring is of type II: the symmetry of the electron ground state is X. Above this threshold, it transitions to type I: the symmetry of the electron ground state is Γ. Also, the effects of the electric field on the linear and non-linear optical properties of the studied structure illuminated with different incident optical intensities were investigated. There is an increase in the radiative lifetime with a notable decrease in the absorption coefficient and the refractive index with the increase in the intensity of the electric field. It’s noted that the increase in the type II quantum ring lifetime (20%) is greater than that of the type I quantum ring (10 %) due to the confinement of the electron with symmetry Γ in the quantum ring which is not the case with the electron with symmetry X. To the best of our knowledge, this article is the first theoretical study of the influence of lateral electric field on the physical properties of type II GaAs/AlGaAs quantum ring structures.