Electrical passivation and chemical functionalization of SiC surfaces by chlorine termination

We have developed a straightforward plasma-based method which yields chlorine-terminated n-type 6H-SiC surfaces. Atomic force microscopy shows that the surface roughness is not affected by the plasma processing. Additionally, x-ray photoelectron spectroscopy reveals a significant reduction in oxygen, and a corresponding rise of chlorine core level intensities, following halogen termination. Contact potential difference and surface photovoltage measurements show formation of negative surface dipoles and approximately flat band surface potentials after chlorine termination of (0001) n-type 6H-SiC (built-in voltage Vbi<20 meV). Starting from halogenated surfaces, we demonstrate both ultraviolet light-induced and thermally-induced functionalization with alkene-derived self-assembled organic monolayers.