Probable atomic structure of reconstructed Si(001)2×1 surfaces determined by low-energy electron diffraction

A LEED intensity analysis of the Si(001)2*1 structure leads to exclusion of two of the most widely discussed models for surface reconstruction. These are models involving surface dimers or surface vacancies. A different model is presented that provides acceptable agreement between calculated and observed intensity spectra. The model is based on the idea of conjugated surface chains advanced by Seiwatz (1964), and involves distortions of both the first and the second atomic layers. The model is consistent with the rare observation of four-fold periodicities on Si(001) and suggests that small surface concentrations of carbon may be important.