Influence of ion energy and substrate temperature on the optical and electronic properties of tetrahedral amorphous carbon ({ital ta}-C) films

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364000· OSTI ID:435098

Chhowalla, M ^[1]; Robertson, J; Chen, C W ^[2]; Silva, S R ^[3]; Davis, C A ^[4]; Amaratunga, G A ^[1]; Milne, W I ^[2]

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1. University of Liverpool, Department of Electrical Engineering and Electronics, Liverpool L69 3BX (United Kingdom)
2. University of Cambridge, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)
3. University of Surrey, Department of Electronics and Electrical Engineering Guildford, Surrey GU2 5XH (United Kingdom)
4. Plasma Research Laboratory, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 2601 (Australia)

The properties of amorphous carbon (a-C) deposited using a filtered cathodic vacuum arc as a function of the ion energy and substrate temperature are reported. The sp{sup 3} fraction was found to strongly depend on the ion energy, giving a highly sp{sup 3} bonded a-C denoted as tetrahedral amorphous carbon ({ital ta}-C) at ion energies around 100 eV. The optical band gap was found to follow similar trends to other diamondlike carbon films, varying almost linearly with sp{sup 2} fraction. The dependence of the electronic properties are discussed in terms of models of the electronic structure of a-C. The structure of {ital ta}-C was also strongly dependent on the deposition temperature, changing sharply to sp{sup 2} above a transition temperature, T{sub 1}, of {approx}200{degree}C. Furthermore, T{sub 1} was found to decrease with increasing ion energy. Most film properties, such as compressive stress and plasmon energy, were correlated to the sp{sup 3} fraction. However, the optical and electrical properties were found to undergo a more gradual transition with the deposition temperature which we attribute to the medium range order of sp{sup 2} sites. We attribute the variation in film properties with the deposition temperature to diffusion of interstitials to the surface above T{sub 1} due to thermal activation, leading to the relaxation of density in context of a growth model. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 435098
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 1 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
CARBON
COATINGS
DIFFUSION
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
ENERGY DEPENDENCE
ENERGY GAP
INTERSTITIALS
ION COLLISIONS
OPTICAL PROPERTIES
PLASMONS
TEMPERATURE DEPENDENCE
THIN FILMS