Determination of the local electronic structure of atomic‐sized defects on Si(001) by tunneling spectroscopy

Tunneling spectroscopy and voltage‐dependent scanning tunneling microscopy have been used to study the geometry and electronic properties of atomic‐sized defects on the Si(001) surface. Individual dimer vacancies are shown to be semiconducting, consistent with the π‐bonded defect model of Pandey. Another type of characteristic defect is found which gives rise to strongly metallic tunneling I–V characteristics, demonstrating that it has a high density of states at the Fermi level and is likely active in Fermi level pinning on Si(001). Spatially dependent I–V measurements and tunneling barrier height measurements also directly reveal the spatial extent of this metallic character and provide direct measures of the ‘‘size’’ of the defects.