Anisotropy of the electron energy levels in InxGa1−xAs/GaAs quantum dots with non uniform composition

Compositional mapping of semiconductor quantum dots and rings

“…Strain and interdiffusion within the rings were determined with GID experiments. A marked difference was found between radial scans recorded close to the (220) and (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) Bragg reflections. Based on the symmetry of the ring shape and on FEM simulations, this asymmetry in the scans was attributed to different In contents in the rims of the QR in the two ⟨110⟩ directions.…”

“…We would like to stress however briefly that such models have been developed [12] soon after the first experimental evidence for intermixing had been published, and they have been useful in contributing to a better understanding of the associated phenomena [13], by for example allowing one to calculate anisotropies in the dots' energy levels [14]. In the last years these models have been further refined [15,16].…”

Energy dependence of the electron‐hole in‐plane anisotropy in InAs/GaAs quantum dots

“…This is due to the fact that the electron and hole envelopes amplitudes near the QD interface decrease with increasing QD radius. We have also found that ħδ  is roughly independent upon the QD height if V P = 0; in the presence of a piezoelectric contribution, on the contrary, ħδ  becomes much more sensitive to the QD height: we calculate ħδ  ≈ 72 µeV (22 µeV) for h = 4 nm (1.5 nm), with |V P | = 40 meV [13]. This variation of h corresponds to a variation of about 78 meV in the energy of the interband transition, in good quantitative agreement with the experimental variations in Fig.…”

Energy dependence of the electron‐hole in‐plane anisotropy in InAs/GaAs quantum dots

“…This is due to the fact that the electron and hole envelopes amplitudes near the QD interface decrease with increasing QD radius. We have also found that ηδ  is roughly independent upon the QD height if V P = 0; in the presence of a piezoelectric contribution, on the contrary, ηδ  becomes much more sensitive to the QD height: we calculate ηδ  ≈ 72 µeV (22 µeV) for h = 4 nm (1.5 nm), with |V P | = 40 meV [13]. This variation of h corresponds to a variation of about 78 meV in the energy of the interband transition, in good quantitative agreement with the experimental variations in Fig.…”

“…The electron and hole are subject to both a piecewise constant confining potential and a piezoelectric contribution. This latter is described by a phenomenological function with lobes of positive and of negative values forming each a tetrahedron with respect to the QD, and maximum value |V P | around the top and the bottom corners of the QD, as results from more elaborate calculations [13]. The ground electron and hole envelopes are products of three gaussian functions with four variation parameters [14].…”