Exciton wave function localization and exciton diamagnetic coefficient in semiconductor quantum rings without reflection symmetry

Abstract

We theoretically study how reflection asymmetry affects the neutral exciton diamagnetic coefficient in selfassembled InGaAs/GaAs semiconductor wobbled quantum rings. The previously proposed mapping method is used to simulate the exciton wave function and energy in the rings. The description is suited to clarify the important question of the exciton diamagnetic coefficient stability in the rings with broken reflection symmetry. Our simulation results confirm that the exciton wave function of the reflection symmetrical (balanced) wobbled ring is distributed equally over two potential valleys corresponding to the hills in the ring's shape. At the same time, even a very small reflectional imbalance in the geometry and (or) material content of the wobbled rings destroys the ringlike shape of the exciton wave function and causes the localization of the function in one of the potential valleys of the ring (dotlike shape of the exciton wave function). This leads to a rapid decrease of the exciton diamagnetic coefficient. Our calculation results are in good agreement with recent experimental observations.

Magnetic field control of the intraband optical absorption in two-dimensional quantum rings

“…As a final remark of this part of our discussion, let us note that at A = 1, the intensity-induced dip is located at x = x 0 and its magnitude is equal to zero, as it elementary follows from Eq. (30).…”

“…[14][15][16]18 Beside quantum ring, a flexibility of the model allows, by the variation of the parameters a i , 15 to describe a quantum dot 21 (QD) if a 2 = 0, an isolated QAD 13 (a 1 = 0), one-dimensional ring [when ρ V = const and the value of ω V = 8a 1 /m * (m * is carrier effective mass) tends to infinity, ω V → ∞] or two-dimensional straight wire (ω V = const and ρ V → ∞). Among other models of quantum rings and QDs, 19,[22][23][24][25][26][27][28][29][30] the most popular is the displaced parabola potential of the form…”

Tuning of the electrongfactor in defect-free GaAs nanodisks

“…Therefore, we adopt a gauge-originindependent definition for the vector potential (see Ref. [58], and references therein): A(r) = B × (r −r)/2, wherer stands for the expectation value of the position of the electron in the ground state. Using this gauge and Eqs.…”

“…Now one can solve the system of nonlinear equations (21) numerically and obtain the dependence of the electron energy (including excited states) on the magnetic field [32,48]. Alternatively, in this paper, to analyze the electron effective g-factor properties at the weak magnetic field, we deploy the advantage of the simulation of the expectation values of the g-tensor components when B → 0 [58][59][60]. Therefore, to simulate and analyze the g-factor tensor for the ground state of the electron confined in the NDs, we first solve the nonlinear Schrödinger equation with the Hamiltonian presented by Eq.…”

Effect of confining potential on the exciton stability at various locations in a parabolic and square quantum ring

“…When subjected to external perturbations like temperature, pressure, electric and magnetic field these systems explore the confined states of electron and exciton which reveal the science of ultrafast devices [12][13][14][15][16][17][18]. Exciton dynamics in a stacked InGaAs/GaAs QR under resonant excitation [19] and diamagnetic coefficient in InGaAs/GaAs semiconductor quantum rings without reflection symmetry has been already studied [20].…”