Séminaire

Mardi 17 Avril 2018 à 11h00.

Continuum modeling of semiconductor heteroepitaxial growth including both elastic and plastic relaxation

''Integration of different semiconductors (such as GaAs or Ge) on Si opens up the possibility to exploit superior transport properties while maintaining the mainstream silicon technology. Lattice-mismatched heteroepitaxy is however difficult to control and computer simulations can help in reducing the experimental growth- parameter space to be sampled when searching for optimal deposition conditions. Continuum simulations of heteroepitaxial growth [1] can tackle much longer temporal and spatial scales with respect to atomistic approaches, allowing one to match experimental conditions. Such approaches are widely exploited in the literature to simulate the Asaro-Tiller-Grinfeld instability and island formation in lattice- mismatched heteroepitaxy. Here we describe a suitable extension [2] allowing for the simulation of growth also in the presence of misfit dislocations. We call that such defects are always present in (thick enough) lattice- mismatched films, providing a key channel for strain release. Our results obtained for Ge/Si(001) growth well compare with experiments, allowing for a proper interpretation of several phenomena including oscillations in island aspect ratio (see Figure) [3,4]. Present limitations and a few interesting perspectives are critically discussed. [1] R. Bergamaschini, M. Salvalaglio, R. Backofen, A. Voigt, and F. Montalenti, Adv. Phys. X 1, 331 (2016). [2] F. Rovaris, R. Bergamaschini, and F. Montalenti, Phys. Rev. B 94, 205304 (2016). [3] F. K. LeGoues, M. C. Reuter, J. Tersoff, M. Hammar, and R.M. Tromp, Phys. Rev. Lett. 73, 300 (1994). [4] M. Stoffel, A. Rastelli, J. Tersoff, T. Merdzhanova, and O. G.Schmidt, Phys. Rev. B 74, 155326 (2006).''