Molecular dynamics simulation of amorphous SiO₂ thin films

Faculty of Applied Science, Hochiminh City University of Technology, 268 Ly Thuong Kiet Street, District 10, 700000 Ho Chi Minh City, Vietnam

^a e-mail: dtntranh@yahoo.com

Received: 8 November 2014
Revised: 7 February 2015
Accepted: 16 March 2015
Published online: 24 April 2015

Abstract

Amorphous SiO₂ thin films have been studied via molecular dynamics (MD) simulations. Thin film models (with two free surfaces) have been obtained by cooling from the melt with reactive force field (ReaxFF) potential. Structural and dynamic properties of the thin films are analyzed via radial pair distribution functions (RPDFs), coordination number distributions, ring statistics and bond-angle distributions. Fraction and role of structural defects have been analyzed and discussed. We also show temperature dependence of various thermodynamic quantities of the system. We found that structure of interior of thin films is close to that of the bulk while surface region contains a large amount of structural defects including dangling bonds, undercoordinated sites, small membered rings. Small and large membered rings concentrate mainly in the surface region and their fraction has a tendency to decrease with decreasing temperature.