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Transport and optical properties of amorphous carbon and hydrogenated amorphous carbon films

 
: Tibrewala, A.; Peiner, E.; Bandorf, R.; Biehl, S.; Lüthje, H.

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Applied surface science 252 (2006), Nr.15, S.5387-5390
ISSN: 0169-4332
International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures (ASCIN) <8, 2005, Stockholm>
International Congress on Thin Films (ICTF) <13, 2005, Stockholm>
Englisch
Zeitschriftenaufsatz, Konferenzbeitrag
Fraunhofer IST ()
amorphous carbon film; electrical conductivity; optical absorption; piezoresistive gauge factor

Abstract
In this paper we report on the electrical and optical properties of amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) films. Resistivity of both types of films decreases with increase in temperature. At lower temperatures (60-250 K) the electron transport is due to variable range hopping for the a-C films. At higher temperatures (300-430 K) it is thermally activated for both types of films. Analysis of the heterojunction between diamond-like carbon (DLC) and bulk silicon (Si) leads to the conclusion that our a-C films are of n-type and our a-C:H films are of p-type. The optical measurements with DLC revealed a Tauc bandgap of 0.6 eV for the a-C films and 1-1.2 eV for the a-C:H films. An Urbach energy around 170 meV could be determined for the a-C:H films. Strain versus resistance plots were measured resulting in piezoresistive gauge factors around 50 for the a-C films and in between 100 and 1200 for the a-C:H films.

: http://publica.fraunhofer.de/dokumente/N-48650.html