Molecular dynamics simulations of epitaxial silicon growth by nanocluster deposition

by Roni Ilmola

Institution: University of Helsinki
Year: 2015
Keywords: Teoreettinen fysiikka
Record ID: 1144563
Full text PDF: http://hdl.handle.net/10138/154314


Surface growth by using nanocluster deposition has attracted a lot of attention in recent years due to possibilities to affect electronic properties of the resulting thin films. Industry is interested in this method because with cluster deposition it is possible to manufacture thin films much faster than by using single atom deposition. In some cases, nanocluster deposition is the only method by which thin films have been able to be deposited successfully. I have studied Si20 cluster deposition on the Si(0 0 1) surface. I used molecular dynamics simulations to simulate epitaxial silicon growth at temperatures 300 K, 500 K, 700 K, 1000 K, 1300 K and 1600 K. I used two potential models to do this, the Tersoff and the Stillinger-Weber potentials. This work focuses on the differences in the results of these potential models at various temperatures. All the atoms in the cluster had 1 eV of energy. I observed that the growth is stronger with the Stillinger-Weber potential almost at every temperature. At 300 K no epitaxial growth was seen and at 1600 K the substrate melted. I observed almost complete epitaxial growth with the Stillinger-Weber potential, whereas with the Tersoff potential there was an amorphous layer on top of the crystalline region. The epitaxial growth didn’t originate from the diffusion as much as from the rearrangement of atoms at the amorphous-crystalline interface.