Origin of surface metallization of Si(001) at high temperatures

초록

Surface metallization of Si(001) has been observed at high temperatures, but its explanation is controversial. Such a temperature-induced metallization can be explained in terms of a symmetric-dimer model where symmetric dimmers are alternately displaced up and down along the dimmer rows. We find that this symmetric-dimer model has an electronlike Fermi surface around the G point and a hole pocket centered at the K1/2 point, in good agreement with angle-resolved photoemission spectroscopy data. Since the p(2x2) symmetric-dimer structure is more favored over the conventional p(2x1) symmetric-dimer structure, its presence may be confirmed by a more detailed analysis of recent reflection high-energy electron-diffraction data which showed the phase transition from a buckled- to a symmetric-dimer structure at high temperatures.