STEP SMOOTHING AND SURFACE VACANCY REACTIONS ON INP(110) AND GAP(110) OBSERVED BY SCANNING-TUNNELING-MICROSCOPY

Tip-induced reactions changing the structure and electronic states of steps and vacancies through local mass transport on cleaved InP(110) and GaP(110) surfaces were studied by STM. Steps one atomic layer high on n-doped surfaces showed a progressive smoothing of step edges during continuous scanning. On the flat part of the surfaces point defects were created under the same experimental conditions and were identified as vacancies and vacancy clusters. Single P vacancies were converted into double vacancies, which were found to be the most stable configuration induced on n-doped surfaces under the influence of scanning, while on p-doped material single vacancies were stable. The double vacancies could, however, change reversibly under scanning into a new defect consisting of four vacancies with a triangular structure.