Molecular dynamics of nanoscale layered structures

Abstract

We have performed computer simulations using molecular statics and dynamics techniques. The purpose of the present work is to study the structure and elastic behavior at the interfaces between dissimilar materials as well as the stability and the growth mode of the epitaxial NiAl film on a zinc-blend structured material. By considering the energetics at the interface, we found that the most stable NiAl film is obtained when ∼1 monolayer of Ni is predeposited prior to the codeposition of Ni and Al atoms. Based on this, we propose an interface model structure for NiAl/AlX (where X is a group V element). Also, careful examination of interface structures for the same systems revealed anomalous atomic relaxations, which cannot be expected from the continuum elasticity. In real time epitaxial growth simulations by molecular dynamics, the effect of several growth parameters such as the interface chemistry, temperature, and misfit strain, along with the characteristic properties at the surface were studied. It has been suggested that the interface chemistry is extremely important in the epitaxial growth of binary films. These theoretical results are verified by subsequent experiments by x-ray double crystal diffractometry for specially grown samples using molecular beam epitaxy, and show excellent agreement.