The C 1$s$ core level spectroscopy of carbon atoms at the surface SiC/Si(111)-4$^\circ$ layer and Cs/SiC/Si(111)-4$^\circ$ interface

Photoemission studies of the electronic structure of the Cs/nano-SiC/Si(111)-4$^\circ$ nanointerface are for the first time carried out with the use of synchrotron radiation in the photon energy range 120–450 eV. The in situ experiments are conducted in the case of submonolayer Cs coating of the surface of an epitaxial SiC layer grown on the vicinal surface Si(111)-4$^\circ$ by a new method of substrate-atom substitution. Modification of the valence-band spectra and the C 1$s$ and Si 2$p$ core levels is studied. The appearance of Cs-induced surface states, with binding energies of 1.2 and 7.4 eV, and a sharp change in the spectrum of the C 1$s$ core level with the appearance of two additional modes are found. The evolution of the spectra shows that the Cs/nano-SiC/Si(111)-4$^\circ$ interface is formed due to charge transfer from Cs adatoms to surface atoms at terraces and steps of the vicinal surface. It is found that the structure of the C layer is nontrivial and involves energetically different carbon states.