Premium
Growth Mode on an Adsorbate Precovered Substrate
Author(s) -
Paunov M.
Publication year - 1998
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/(sici)1521-4079(1998)33:2<165::aid-crat165>3.0.co;2-3
Subject(s) - adsorption , chemical physics , surface energy , chemistry , crystal growth , layer (electronics) , crystal (programming language) , lattice (music) , condensed matter physics , thermodynamics , crystallography , materials science , nanotechnology , physics , computer science , acoustics , programming language
Simple lattice model is used to consider the influence of adsorption on the thin film growth mode. It is found that the presence of an adsorbate in a heterogeneous system does not change the general form of the Wulff‐Kaischew theorem provided the surface sensitive quantities are correctly defined. An extended criterion for the layer‐by‐layer growth mechanism is obtained. Contrary to the Bauer's 3‐σ rule in the generalized criterion enter interfacial free energies only whereby all surface free energies are absent. As a consequence the change of the growth mode (3D → 2D) upon adsorption could be explained by purely thermodynamic reasons. It is shown also that the adsorbate changes drastically the chemical potential of the underlying layer rendering it close to the chemical potential of the infinitely large three‐dimensional crystal. Therefore, the growth on a preadsorbed foreign substrate takes place practically as on an own substrate. An exchange process between incoming atoms and adsorbate particles keeps the adsorbate predominantly on the top of the growing surface rather than in the bulk of the film. The driving force of this process is the free energy difference between “in bulk” and “on surface” configurations of the system. The phenomenon reveals the thermodynamic principle that the spontaneous processes lower the free energy and render the system to its ground state.