Eur. Phys. J. B 66, 175-183 (2008)
https://doi.org/10.1140/epjb/e2008-00410-8

Equilibrium shape and size of supported heteroepitaxial nanoislands

¹ Department of Engineering Physics, P.O. Box 1100, Helsinki University of Technology, FIN-02015 TKK, Espoo, Finland
² Institute of Physics and Technology, Yaroslavl Branch, Academy of Sciences of Russia, Yaroslavl, 150007, Russia
³ Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12245-970 São José dos Campos, SP, Brasil
⁴ Department of Physics, P.O. Box 1843, Brown University, Providence, RI, 02912-1843, USA

Corresponding author: ^a jhj@fyslab.hut.fi

Received: 6 June 2008
Revised: 5 September 2008
Published online: 8 November 2008

Abstract

We study the equilibrium shape, shape transitions and optimal size of strained heteroepitaxial nanoislands with a two-dimensional atomistic model using simply adjustable interatomic pair potentials. We map out the global phase diagram as a function of substrate-adsorbate misfit and interaction. This phase diagram reveals all the phases corresponding to different well-known growth modes. In particular, for large enough misfits and attractive substrate there is a Stranski-Krastanow regime, where nano-sized islands grow on top of wetting films. We analyze the various terms contributing to the total island energy in detail, and show how the competition between them leads to the optimal shape and size of the islands. Finally, we also develop an analytic interpolation formula for the various contributions to the total energy of strained nanoislands.