Scanning-tunneling-microscope tip-induced migration of vacancies on GaP(110)

Scanning-tunneling-microscope tip-induced migration of divacancies is observed on n-doped GaP(110). The motion occurs only at negative polarity of the tunneling voltage and along the [11{}0] direction, independent of the scanning direction, and is thus purely nonthermal. It is suggested that a field-induced reduction of the barrier for the migration initiates the motion. A quantitative analysis of the migration indicates long-lived excited states, consistent with charged trap states in doped semiconductors.