Metastable and excited states of the C defects of Si(001)

Dynamic characteristics of the C defect were studied by consecutive scanning tunneling microscopy observations. Not only the transformation of the C defect into a C2 defect but also the reverse transition, a C2 to C structural change, and a more complicated C to C2-C2 transformation were observed. All of the experimental results suggest that the C2 defect is a metastable and excited state of the C defect that has a similar electronic structure to the C defect. Extensive scanning tunneling spectroscope measurements reveals that there exists several (at least two) types of C defect, which we believe to represent metastable states of the C defect. Our interpretation is that there are two atoms (probably silicon) in the top layer of the C defect which are weakly bound to the layer beneath, and possibly take several configurations. Each of the configurations is observed as a metastable state of the C defect. (C) 1999 Published by Elsevier Science B.V. All rights reserved.