Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)

O 29.63: Poster

Mittwoch, 29. März 2006, 14:30–17:30, P2

Surface conductivity induced by fullerenes on diamond — •Paul Strobel, Jürgen Ristein, and Lothar Ley — Institut für Technische Physik, Universität Erlangen-Nürnberg, Germany

The surface conductivity of hydrogen terminated diamond under atmospheric conditions is a well known phenomenon. The atmospheric adsorbents induce a near-surface hole gas resulting in a surface conductivity of diamond. In the present work we investigated C60 and fluorinated derivatives C60F18, C60F36, and C60F48 as alternative electron acceptors on the diamond surface. The electron affinity of the fluorinated fullerenes increases with the number of F-atoms from 2.7eV for C60 up to 4.1eV for C60F48. As a consequence, the doping efficiency increases in the same order and reaches unity for C60F48, i.e. each adsorbed C60F48 accepts one electron from the diamond. With device applications in mind, we further investigated the thermal stability of fullerene induced surface conductivity on diamond. Due to the increasing vapour pressure of the fullerenes with increasing fluorination the dosorption temperature in high vacuum decreases from 200^∘C for C60 to RT for C60F48. A notable improvement of thermal stability was achieved by passivation of fluorinated fullerenes by different dielectric layers (SiO, CaF2). In the case of C60 we observed an auto stabilisation up to 350^∘C in high vacuum after light, air, and temperature promoted polymerisation.