ELECTRICAL CHARACTERIZATION OF PLASMA-DEPOSITED HYDROGENATED AMORPHOUS-CARBON FILMS

An r.f.-plasma-enhanced chemical vapour deposition apparatus for the preparation of doped hydrogenated amorphous carbon (a-C:H) thin films built at the Institut fur Solarenergieforschung is presented. Undoped samples of a-C:H prepared in this reactor and nitrogen-doped samples prepared in a similar reactor under similar conditions at the Battelle Institute were investigated. They showed a field-strength- and time-dependent conductivity. Measurements on a doped specimen between 100 and 280 K revealed a temperature dependence of the conductivity which is consistent with hopping models. The aim of these investigations is to understand film growth and electrical conduction mechanisms with respect to solar energy conversion applications.