Structure transformation of the C defects observed at low temperature (80 K)

The dynamical characteristics of the C defect at low temperature (80 K) wer e studied by sequential scanning tunneling microscopy observations. We foun d that the: C defect frequently transforms into a another type of defect te rmed as the C-2(LT) defect. In addition, the reversal C-2(LT) to C defect s tructural transformation was observed which implies that the C-2(LT) defect is a metastable state of the C defect. The observed structural transformat ion was completely different from that observed at room temperature. We int erpret that structural transformation associated with a change in the phase of the defect is suppressed at low temperatures because it disturbs the or dering of the surrounding buckled dimers.