Silicon adatom chains and one-dimensionally confined electrons on 4H-SiC: The (2 × 1) reconstruction

The electronic and atomic structure of the 4H-SiC ( 1 1 ¯ 02 ) - ( 2 × 1 ) surface was investigated. Photoemission data indicate that the surface contains about 2 Si layers on top of the bulk layers. Scanning tunneling microscopy images show that these adlayers are terminated by an ordered array of adatom chains separated by the unit cell size. An electronic surface state located at a binding energy of 0.8 eV shows one-dimensional confinement with dispersion only along the chains. Based on the experimental observations, a tentative (2 × 1) surface model is derived with the surface terminated by alternating chains of Si adatoms and Si dimers in between.