Search

SiHx (x = 1,2,3) ions impact on Si(001)(1 x 1):H and Si(001)(2 x 1):H surfaces has been studied by classical molecular dynamic simulations, considering an energetic range for the impinging species from 5 to 15 eV. Despite the initial full H coverage a high sticking coefficient has been obtained for all the species under investigation. A considerable fraction of adsorption events causes H removal from the surface while for other simulations a soft landing mechanism of the ions has been observed. Few representative minima for SiH2/ Si(0 01)(2 x 1):H were re-converged by ab initio calculations in order to check the reliability of our results. (C) 2007 Elsevier B.V. All rights reserved.

We propose an extension of the well-known flat-island approximation in (1 1) dimensions which, while keeping simple analytical relations, allows one to better describe the strain field on the facets of steeper islands, and on the wetting layer between them. The results of atomistic molecular dynamics simulations using the Tersoff potential are used as a benchmark. The simple continuum approach is also shown to predict the correct trend of the strain gradients characterizing closely-spaced interacting islands, which has been recently observed to produce lateral motion of large Ge dots on Si(001). (c) 2006 Elsevier B.V. All rights reserved.

Using the first-order density matrix of an infinite barrier model of a metal surface, the exchange energy density can be evaluated exactly as a function of the distance z from the barrier. This result is compared with the local approximation -3 4 e 2 (3/π) 1 3 [ρ(z)] 4 3 where ρ is the electron density in the model. The local approximation follows the exact result quite closely at all z but leads to a large percentual error in the integrated surface exchange energy.