Reinterpretation of the scanning tunneling microscopy images of Si(100)-(2 x 1) dimers

We revisit and refine the interpretation of the scanning tunneling microscopy (STM) images of the Si(100) dimers, based on results from an extensive set of STM observations carried out at low temperature (80 K) and total-energy calculations of Si(100) surfaces. The interpretation addresses some unresolved questions and brings much experimental and theoretical research into unanimous agreement. We show that tunneling from surface resonances and bulk states seriously contributes to the STM images within usual tunneling conditions. In the empty state, tunneling from these states overwhelms tunneling from the localized pi* surface state, which STM is generally believed to observe.