TITLE

Disorder and Urbach energy in hydrogenated amorphous carbon: A phenomenological model

AUTHOR(S)
Fanchini, G.; Tagliaferro, A.
PUB. DATE
August 2004
SOURCE
Applied Physics Letters;8/2/2004, Vol. 85 Issue 5, p730
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We develop a phenomenological model describing the structural and topological effects of the disorder in hydrogenated amorphous carbons (a-C:H), through the analysis of the Raman G-peak width and the optical absorption spectra, providing information on the densities of electronic π ad π* states (πDOS). We show that the Urbach energy is not related to topological disorder but to the Gaussian width (σπ) of the πDOS, peaked at ±Eπ energies above/below the Fermi level. σπ, on its turn, is not related in a straightforward manner to the disorder. The disorder is better represented by the σπ/Eπ ratio, expressing the disorder-induced narrowing of the Tauc optical gap.
ACCESSION #
13926114

 

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