Influence of tip-surface interactions and surface defects on Si(100) surface structures by low-temperature (5 K) scanning tunneling microscopy

The Si(100) surface structures on n-type degenerately doped samples (ρ∼0.005Ωcm) have been investigated with a scanning tunneling microscope (STM) at very low temperature (∼5 K). We have developed a method to monitor quantitatively the proportion of the various observed surface structures [p(2×2), c(4×2) and flickering]. This study has been performed as a function of the tunnel current and the presence (or not) of surface defects in the observed areas. The normal surface areas having a low density of defects (∼1%) have been observed to vary from the p(2×2) to the c(4×2) structures when the tunnel current increases. This indicates that the STM tip-surface interaction strongly influences the observed structures. Furthermore, surface areas completely free of any defects are dominated by flickering structures.