Title Identification of Ternary Phases in TiBC/a-C Nanocomposite Thin Films: Influence on the Electrical and Optical Properties
Authors David Abad, Manuel , Sanjines, Rosendo , ENDRINO ARMENTEROS, JOSÉ LUIS, Gago, Raul , Andersson, Joakim , Carlos Sanchez-Lopez, Juan
External publication Si
Means Plasma Process. Polym.
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
SJR Impact 1.35600
Web https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960223700&doi=10.1002%2fppap.201000182&partnerID=40&md5=4e5a43d89963a91f804a7a256a94a42e
Publication date 22/07/2011
ISI 000293273400001
Scopus Id 2-s2.0-79960223700
DOI 10.1002/ppap.201000182
Abstract The local structure of TiBC and amorphous carbon (a-C) nanocomposite films (TiBC/a-C) was correlated with their optical and electrical properties. TiBC/a-C films with increasing C content were deposited by magnetron co-sputtering from TiC:TiB2 (60: 40) and graphite targets. Chemical composition is determined by electron energy-loss spectroscopy. Grazing incidence X-ray diffraction reveals that the microstructure of the films is amorphous with small nanocrystallites emerging by increasing the C content that could be attributed to the formation of ternary (TiBxCy) or mixed binary (TiB2 and TiC) phases. Further information was then obtained by studying the chemical bonding by measuring the near-edge fine structure (NES) by electron energy-loss (B K-, C K-, and Ti L-edges) and X-ray absorption (B K-and Ti L-edges) spectroscopies. The NES analysis indicates the formation of a nanocrystalline ternary TiBxCy compound concomitant with the segregation of an a-C phase as the carbon content is increased. The optical properties were studied by spectroscopic ellipsometry and the electrical resistivity was measured by the Van der Pauw method between 20 and 300 K. The films continuously lose their metallic character in terms of optical constants and resistivity with increasing carbon content. Theoretical fitting of the electrical properties using the grain-boundary scattering model supported the formation of a nanocomposite structure based on a ternary TiBxCy phase embedded in a matrix of a-C. The electron transport properties are mainly limited by the high density of point defects, grain size, and transmission probability.
Keywords amorphous carbon; EELS; electrical properties; nanocomposites; optical properties; structure; TiBC coatings; XAS
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