Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 11: Carbon: Nanotubes, Diamond and Silicon Carbid

HL 11.2: Talk

Monday, March 26, 2012, 12:00–12:15, EW 203

Electrical and Chemical Passivation of 6H-SiC Surfaces by Chlorine Termination — Sebastian Schoell, •Matthias Sachsenhauser, John Howgate, Jose Garrido, Martin Brandt, Martin Stutzmann, and Ian Sharp — Walter Schottky Institut, Technische Universitaet Muenchen, Garching, Germany

In recent years, growth and processing of SiC has considerably improved. However, practical ways of chemical and electrical passivation of SiC surfaces are still rare. In particular, etching in HF yields hydroxylated surfaces with high defect densities. Here, we utilize plasma processing methods to achieve chlorine-terminated n-type (0001) 6H-SiC surfaces. Static water contact angle and atomic force microscopy show a transition of the wetting behavior from hydrophilic to hydrophobic surfaces following chlorine termination without affecting the surface roughness. Accordingly, X-ray photoelectron spectroscopy reveals an increased chlorine core level intensity together with a significant reduction of oxygen. Chlorine desorption at elevated temperatures of up to 425°C suggests saturation of terminal atoms rather than near surface incorporation of chlorine. The electronic properties of the plasma treated surfaces are examined with contact potential difference and surface photovoltage measurements and show the formation of negative surface dipoles as well as approximately flat band surface potentials, indicative of a successful termination of electrically active surface defect sites. Finally, we demonstrate that the halogenated surfaces enable the formation of functional self-assembled monolayers providing controlled chemical functionalities for bioelectronic and biosensor applications.