FIELD ION-SCANNING TUNNELING MICROSCOPY OF ALKALI-METAL ADSORPTION ON THE SI(100) SURFACE

We have constructed a scanning tunneling microscope (STM) equipped with a field ion microscope (FIM), by which one can monitor and shape the STM probe tip on an atomic scale in situ in the STM chamber. Taking advantage of a well-defined tip prepared by a FIM, we have greatly improved the stability and reproducibility of the performance of the STM. Li and K adsorption on the Si(001) 2x1 surface has been investigated by field ion-scanning tunneling microscopy (FI-STM). The STM images have shown that at the initial stage of adsorption, Li (K) atoms (1) adsorb on top of one of the dimer-forming Si surface atoms and (2) stabilize the asymmetric (buckled) dimerization, and (3) form linear chains, perpendicular to the substrate 2x1 dimer rows. Our observations suggest that alkali metal adsorption on the Si(001) 2x1 surface may be significantly different from the conclusions of earlier reports. © 1990, American Vacuum Society. All rights reserved.