Second-layer nucleation in coherent Stranski-Krastanov growth of quantum dots
arXiv:1107.5677 · doi:10.1103/PhysRevB.84.195417
Abstract
We have studied the monolayer-bilayer transformation in the case of the coherent Stranski-Krastanov growth. We have found that the energy of formation of a second layer nucleus is largest at the center of the first-layer island and smallest on its corners. Thus nucleation is expected to take place at the corners (or the edges) rather than at the center of the islands as in the case of homoepitaxy. The critical nuclei have one atom in addition to a compact shape, which is either a square of i*i or a rectangle of i*(i-1) atoms, with i>1 an integer. When the edge of the initial monolayer island is much larger than the critical nucleus size, the latter is always a rectangle plus an additional atom, adsorbed at the longer edge, which gives rise to a new atomic row in order to transform the rectangle into the equilibrium square shape.
6 pages, 4 figures. Accepted version, minor changes
References in corpus (5)
- Equilibrium nano-shape changes induced by epitaxial stress (generalised Wulf-Kaishew theorem)
- Nucleation of Ge quantum dots on the Si(001) surface
- Thermodynamic driving force of formation of coherent three-dimensional islands in Stranski-Krastanov growth
- Forbidden island heights in stress-driven coherent Stranski-Krastanov growth
- Quantum-dot nucleation in strained-layer epitaxy: minimum-energy pathway in the stress-driven 2D-3D transformation