Adsorption and Nucleation of Boron Triiodide on Tungsten
Abstract
The physical vapor deposition of boron triiodide on macroscopic tungsten substrates was studied by using a Volmer-type apparatus. Data obtained were treated by a modification of the method of Pound. Results showed that nucleation of BI3 on tungsten was preceded by multilayer adsorption. The critical concentration of adsorbed monomers required for nucleation was 1.0 × 1015 molecules/cm2. Adsorption was time dependent at low temperatures. A steady state between impingent and desorption fluxes occurred at temperatures equal to or precedes 160°K. The nucleation data are described, using a disk model for the critical nucleus. The following Gibbs free energies were determined: (a) for formation of the critical nucleus, 1700 cal/mole; (b) for surface-diffusion activation, 1900 cal/mole; (c) for desorption activation, 11700 cal/mole; and (d) the critical volume free-energy change, - 72 cal/cm3. Weaknesses in both the macroscopic thermodynamic and statistical mechanical theories together with alternative interpretations of nucleation data are discussed. © 1968.
Recommended Citation
P. D. Ownby and R. D. Gretz, "Adsorption and Nucleation of Boron Triiodide on Tungsten," Surface Science, Elsevier, Jan 1968.
Department(s)
Materials Science and Engineering
International Standard Serial Number (ISSN)
0039-6028
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 1968 Elsevier, All rights reserved.
Publication Date
01 Jan 1968
