Structure of double-atomic-height steps in Si(001) vicinal surfaces observed by scanning tunneling microscopy☆

Abstract The structure of single- and double-atomic-height steps in vicinal Si(001) surfaces for miscut angles of 0.5° and 4.5° from the (001) plane along [110] has been investigated by scanning tunneling microscopy (STM). We observed several modified step structures along a given step for single- and double-atomic-height steps. The double-atomic-height steps, with a regular spacing of 30 A along [110] for the misoriented surface by 4.5°, show various step configurations with mixing of single- and double-atomic-height steps. Meander of double-atomic-height steps is induced by formation of missing dimer defects and shoulders of a single-atomic-height caused by surface migration of dimer-row segments from upper to lower terraces adjoining the step. Formation mechanisms for various configurations of double-atomic-height steps and step height transitions in Si(001) are described based on the step structures observed by STM.