▎ 摘　　要

The subsurface structures on top of a 4H-SiC(0001) at two defined thermal graphitization stages, the graphene precursor terminated with (6 root 3 x 6 root 3)-R30 degrees periodicity and single-layer graphene (SLG), were characterized by photoelectron holography. The local atomic configuration at the graphene precursor layer and single-layer graphene (SLG) as well as the interface buffer layer were reconstructed. The existence and similarity of local buckling were confirmed on both the precursor and buffer layers. The vertical position of SLG seen from the buffer layer was observed with the similar height of graphite: 0.33 +/- 0.02 nm. The stacking registry of SLG on the buffer layer was determined to be AB type. (C) 2014 Elsevier B.V. All rights reserved.