On the Adsorption of Gases on Silicon Carbide: Simple Estimates
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The adsorption of atomic and molecular nitrogen and ammonia on silicon carbide is considered within two physically different (solid-state and quantum-chemical) approaches. In the solid-state approach, the Haldane–Anderson model is used for the density of states of the SiC 4H and 6H polytypes to demonstrate that the energy of binding to the substrate is 6 and 3 eV for N atoms and N2 molecule, respectively. In the quantum-chemical approach, the model of a surface diatomic molecule is used to find that the binding energy of atomic nitrogen is 6 and 4 eV for adsorption on the C- and Si-edges, respectively. It has been established that the charge transfer between an adsorbate and the substrate may be neglected in all the considered cases. It has been hypothesized that the dissociation of a molecule with the further passivation of its dangling sp3-orbitals with hydrogen atoms takes place for silicon carbide as in the case of ammonia adsorption on Si(100).
Keywords:Haldane–Anderson model surface molecule model charge transfer adsorption energy
The authors are grateful to S.A. Kukushkin for proposing the topic and useful discussions.
CONFLICT OF INTERESTS
The authors declare that they have no conflicts of interest.
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