Figure 7
From: Tunneling spectroscopy of close-spaced dangling-bond pairs in Si(001):H
Our model to explain the measured STS spectra at negative sample voltage (corresponding to a positively charged tip).
The basic ingredient is the assumption that in our p-doped Si(001):H substrate the transitions between positive and neutral charge states of the DBs can occur under moderate applied biases in the presence of the STM tip. In each panel we schematically show an initial state (left) whose dominant charge state can change under the influence of the STM tip (middle-top and bottom) and reaches a final state (right) after tip removal. (Left) The ground state of the “cross” DB pair is positively charged and corresponds to a (+0) configuration. However, the dominant charge state of the positive DB becomes neutral under the measuring conditions. (Right) The “line” DB pair is initially charge polarized, with a (+−) configuration. A similar positive → neutral transition takes place when the initially positive DB is measured. After measurement the DB pairs are left unmodified in agreement with experimental evidence.
