Free-energy model for bonding in amorphous covalent alloys
- Department of Physics, City College of the City University of New York, New York, New York 10031 (US)
A free-energy model (FEM) for bonding in amorphous covalent alloys is developed and applied to the ternary {ital a}-Si{sub {ital x}}N{sub {ital y}}H{sub {ital z}} alloy system. The Gibbs free energy of mixing {ital G}{sub {ital M}}={ital H}{sub {ital M}}{minus}{ital TS}{sub {ital M}} is obtained with use of the quasichemical approach to the thermodynamics of regular solutions. The enthalpy of mixing, {ital H}{sub {ital M}}, is expressed in terms of the nearest-neighbor bond energies, while the entropy of mixing, {ital S}{sub {ital M}}, is given by the number of possible bonding configurations in Si-centered tetrahedra. Chemical ordering (CO) in these alloys is shown to correspond to the preference for Si-N and Si-H bonds at the expense of Si-Si and N-H bonds. The predictions of the FEM are shown to be in good agreement with experimentally determined bond concentrations in {ital a}-Si{sub {ital x}}N{sub {ital y}}H{sub {ital z}} alloy films where, in general, neither the CO ({ital T}=0 K) nor random-bonding limits are valid.
- DOE Contract Number:
- FG02-87ER45317
- OSTI ID:
- 5734332
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Vol. 43:5; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMORPHOUS STATE
BONDING
SILICON ALLOYS
SILICON NITRIDES
ENTHALPY
FREE ENERGY
MATHEMATICAL MODELS
THIN FILMS
ALLOYS
ENERGY
FABRICATION
FILMS
JOINING
NITRIDES
NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
SILICON COMPOUNDS
THERMODYNAMIC PROPERTIES
360603* - Materials- Properties