SCANNING-TUNNELING-MICROSCOPY STUDY OF THE METAL-INDUCED SI(111)3X1 RECONSTRUCTION - EVIDENCE FOR DIMERIZED CHAIN FORMATION

Scanning tunneling microscope (STM) images of the Si(111)3 X 1-Ag interface exhibit a strong bias dependence. A clear dimerization of the Si surface atoms is evident from the 1 V empty state images. The imaged electronic states exhibit either a 3 X 1 or a 6 X 1 periodicity. These results are interpreted on the basis of the recently proposed dimerized chain or conjugated chain model. It is demonstrated that the dimer orientation in every second dimer row of the 3 X 1 reconstruction can be changed using a STM tip, thereby producing a 6 X 1 symmetry. This phenomenon could be similar to the well-known soliton excitations in doped conjugated polymers.