Scanning tunnelling spectroscopy of dangling-bond wires fabricated on the Si(100)-2x1-H surface

The scanning tunnelling microscopy/spectroscopy (STM/STS) of atomic-scale dangling-bond (DB) wires on a hydrogen-terminated Si(100)-2x1-H surface is studied. A single DB and a paired DB on a Si dimer, fabricated by extracting hydrogen atoms from the hydrogen-terminated Si surface, are distinguished by STM and the DB wires are categorized into several types. In the case of DB wires made of paired DBs, the STS shows semiconductive electronic states with a band gap of approximately 0.5 eV. The DB wires made of both single and paired DBs show a finite density of states at Fermi energy and do not show semiconductive band gaps. The results are in good agreement with recent "first-principles" theoretical calculations.