Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 7: Spin-Orbit Interaction at Surfaces I

O 7.6: Talk

Monday, March 22, 2010, 12:30–12:45, H38

In-situ UPS studies into hydrogen terminated surface of amorphous carbon films and its direct effects on electron emission — •Daniel Chua — National University of Singapore, Singapore

The effects of hydrogen terminated surface of single crystal diamond are well known. This imparts unique properties such as p-type transfer doping and enhanced surface conductivity to the diamond films. In this work, the effects of surface hydrogenation on non-hydrogenated tetrahedral amorphous carbon (ta-C) films are systematically studied and for the first time, we report that the hydrogen termination directly leads to a lowering of the turn-on field for ta-C films, resulting in electron emission from an ultra-smooth thin film without any pre-conditioning process. Prior, HREELS confirmed the presence of C-H bonds on the surface after microwave plasma CVD system was used to hydrogenate the surface of the ta-C films. In-situ UPS shows the hydrogen terminated surface reduces the work function by > 1 eV and is highly stable up to 600oC. Surface roughness from an AFM shows minimal changes to the morphology during the various process. Enhancement effects are distinctly observed when the surface hydrogenated ta-C films are directly tip-coated on vertically aligned carbon nanotubes. These hybrid core-shell structures have potential applications as cold cathode source due to the very low turn-on field.