Energy barrier for dimer flipping at the Si(001)-(2 x 1) surface in external electric fields

摘要

Effects of external electrostatic fields, E_(ext), on a barrier in energy for dimer flipping, E_B, at the Si(001) -(2 x 1) surface have been investigated using first-principle total energy calculations. It has been revealed that E_B changes in proportion to E_(ext). This finding suggests that we can turn on and off the flip-flop motions by alternating the polarity of the field with a scanning tunneling microscope (STM) at low temperatures, which is consistent with the recent experimental results. It has also been shown that the c(4 x 2) surface is more stable than the p(2 x 2) even in electric fields typical of STM experiments.