Self-Assembled Quantum Dots: Crossover from Kinetically Controlled to Thermodynamically Limited Growth

Abstract

By means of kinetic Monte Carlo simulations of the self-organized growth of quantum dots in strained semiconductor systems we resolve the seemingly contradictory features of kinetic versus thermodynamic behavior, e.g., with respect to the temperature dependence of the average dot size and their dispersion. We show that the size distribution immediately after deposition is kinetically controlled, with smaller islands for lower temperatures and larger islands for higher temperatures. For longer simulation times the kinetics leads to equilibration, and a crossover effect between the size distributions occurs, which is in good agreement with the predictions of thermodynamics.

Unveiling the Nucleation and Coarsening Mechanisms of Solution-Derived Self-Assembled Epitaxial Ce0.9Gd0.1O2–y Nanostructures

“…However, a large controversy has been generated around the role played by these competing thermodynamic and kinetic mechanisms (e.g. strain relaxation, surface energies, nucleation barriers and atomic diffusion) in the self-assembling and self-organization of epitaxial nanostructures [39][40][41][42] . Essentially, the formation of thermodynamically stable nuclei occurs when they grow beyond a critical size overcoming a nucleation barrier.…”

Semiconductor nanostructures for flying q-bits and green photonics

“…Brilliant high-resolution transmission electron micrographs of InAs/GaAs QDs (Figure 1) that were grown using MOCVD [10,11] reveal indeed a close to perfect selfsimilarity of QDs and confirm the thermodynamic modelling approach [7,8]. Further important theoretical work included kinetic aspects [12] and contributed to a more detailed understanding of QD growth.…”

“…Volume elastic relaxation of coherently strained islands has been discovered and described in detail theoretically in the nineties as an alternative mechanism of total energy relaxation competing with the formation of dislocations [7,8,12]. The total energy E total of a heterostructure latticemismatched system with islands having edges is equal to three contributions: the relaxation of elastic energies, the variations of the surface energies, and the discontinuity of the intrinsic surface stress tensor at the edges.…”

“…In semiconductor epitaxy, the growth of QDs is now well understood [7][8][9][10][11][12]. They are often observed being self-similar and can be formed by self-organized growth on surfaces [9][10][11].…”

Size calibration of strained epitaxial islands due to dipole–monopole interaction

“…They may be called the island nearest neighbors (NN). At high values of the diffusion to deposition rates ratio that we are going to simulate in section 4 the growth is in the thermodynamically controlled regime the distribution of mobile atoms is very close to equilibrium [10,11] so their density can be assessed as…”