PCAM PhD talk series

For the second talk in our online seminar series, we welcome Francesco Montalenti  and Luca Barbisan from the University of Milano-Bicocca. Please contact Katharina to get the link to the next online talk.

17.6. Talk No.2  

15-15:10 Francesco Montalenti: Studying in Milan at the University of Milano-Bicocca (suggestion)

15:10 – 15:45 Luca Barbisan: Vacancy-mediated climbing motion of edge dislocations in Ge/Si films: Atomic-scale insights via molecular dynamics simulations

15:45 – 16:00 discussion

Abstract

Germanium and silicon-germanium alloys are appealing to the microelectronic industry because they display superior properties while maintaining full compatibility with standard silicon technology. Epitaxial deposition of Ge (or SiGe) on Si substrates is unavoidably accompanied by nucleation of dislocations. Reducing the density of such linear defects threading through the film and reaching the free surface is one of the main present goals of the industrial and academic community devoted to the integration of different materials on Si. Understanding the microscopic mechanisms determining the typical arrays of dislocations can surely help in devising strategies for controlling the evolution of the defects. Gathering such knowledge directly from experiments is not straightforward, due to the combined requirements in terms of spatial and temporal resolution.  Computer simulations can therefore offer an important alternative.

In this talk, we shall show that large-scale, classical Molecular Dynamics (MD) simulations are a particularly useful tool to investigate the behaviour of linear defects in Ge/Si films. In particular, we shall present a set of MD simulations aimed at understanding how dislocations in Ge/Si films can move and organize through a combination of gliding and climbing mechanisms, eventually leading to an ordered array of defects at the interface with Si, as experimentally observed upon annealing. The role played by vacancies in largely speeding-up defect motion is emphasized.

Find the list of the first 9 talks here.