Effect of Metal Back Contacts on Tetrahedral Amorphous Carbonc Films Grown Using the Cathodic Arc Process
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EFFECT OF METAL BACK CONTACTS ON TETRAHEDRAL AMORPHOUS CARBON FILMS GROWN USING THE CATHODIC ARC PROCESS. B.S.Satyanarayana@, H.Takahashi*, T.Narusawa* and A.Hiraki. KUT Academic & Industrial Collaboration Centre, Kochi University of Technology, Kochi, 782-8502, Japan. *Electronic and Photonic Systems Engineering Dept. @ Also- Sistec Co Ltd, Nankoku-Shi, Kochi, 783 0014, Japan. ABSTRACT Reported here is a study on the effect of different metal back contacts on the electrical and structural properties of the tetrahedral amorphous carbon (ta-C). The films were grown using a pulsed cathodic arc system. Ta-C films were deposited simultaneously on silicon substrate, precoated with the following metals, namely aluminium (Al), gold (Au), chromium(Cr), molybdenum (Mo), copper (Cu), tungsten (W) and titanium(Ti). The electrical measurements and Raman response show that the back contact does influence the properties of ta-C films. These results are analysed with respect to our earlier report regarding the influence of back contacts on field emission from similar ta-C films. INTRODUCTION Tetrahedral amorphous carbon (ta-C) is being studied with great interest for use in diverse areas including electronics, vacuum microelectronics, sensors, MEMS and tribology.[1-4] The ta-C films have been grown using a wide variety of processes including, Filtered cathodic vacuum arc(FCVA) - direct and pulse source, Pulsed laser ablation deposition (PLAD), Mass selected ion beam(MSIB) deposition and Electron cyclotron wave resonance (ECWR) process. The interest in ta-C films, stems from the possibility of tailoring the material properties, varying from highly diamond-like (sp3)[1-5] to highly graphite-like (sp2)[6] materials including fullerenes[7] and nanotubes[8] by varying the growth conditions. Further in general, most of these processes are room temperature process, allowing for the use of low cost substrates like glass. Considering the amount of ta-C work reported in literature, and the increased importance of ta-C films and carbon films in general, it is surprising to note that there are very few reports on the effect of metal back contacts, on the properties of the ta-C films. Especially with the enhanced interest in carbon based materials for use as field assisted electron emitters[9-15] we believe there is an urgent need for study on the effect of back contacts. In the case of field emitters, the main factors that could influence emission are the barrier or interface at the back, the transport of carrier through the film and the nature of the front surface. Among the three factors mentioned above, the aspect that has been less reported is the effect of back contacts on field emission. One of the first report on the effect of back contacts on field emission from ta-C films was by Hart et.al[16]. They had reported that the emission threshold field did not show any consistent trend or dependence on the back contacts. The threshold field was defined as the field W10.2.1
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n++Si
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