PHOTOELECTRON-SPECTROSCOPY AT CLEAN AND HYDROGENATED C(2X2)-SIC(100) SURFACES

In order to test structure models of the c(2 X 2)-reconstruction, angl e-integrated Valence band spectra at c(2 X 2) and (2 X 1) 3C-SiC(100) surfaces are reported. The surfaces are characterised by X-ray photoel ectron spectroscopy (XPS) and low energy electron diffraction (LEED). Two different preparation techniques for the c(2 X 2)-reconstruction a re compared, and it is shown that both methods yield the same well-def ined ultraviolet photoemission (UPS) spectra. On the (2 X 1)-surface, we find emission from an occupied surface state. On the c(2 X 2)-surfa ce, no unambiguous evidence for a true surface state could be found. H owever, we find a surface resonance below the valence band maximum. Ba nd bending and work function results for the two reconstructions and t he effect of atomic hydrogen on the c(2 X 2)-surface are also reported . (C) 1998 Elsevier Science B.V.