Determination of spherosiloxane cluster bonding to Si(100)-2 x 1 by scanning tunneling microscopy

Scanning tunneling microscopy is used to determine the bonding geometry of the spherosiloxane cluster, H(8)Si(8)O(12) , on Si(100)-2 x 1. The images obtained are consistent with monovertex bonding to the Si(100)-2 x 1 surface via activation of a single Si-H bond. Filled and empty state images show good agreement with calculations of the electron density distribution of the cluster as well as the Psi(2) highest occupied molecular orbital and lowest unoccupied molecular orbital surface plots of the cluster.     

Electronic properties of (2 x 1) and c(4 x 2) domains on Ge(001) studied by scanning tunneling spectroscopy

The surface electronic structure of Ge(001) was studied by scanning tunneling spectroscopy. The measured surface densities of states unequivocally reveal the presence of a metallic state on the (2 x 1) domains, which is absent on the c(4 x 2) domains. This metallic state, so far observed only in integral measurements, is attributed to the flip-flopping dimers that constitute the (2 x 1) domains. Our data also reveal a set of previously unresolved surface states, in perfect agreement with published theoretical predictions.     

Atomic structure of a (2 x 1) reconstructed NiSi2/Si(001) interface

Nickel disilicide/silicon (001) interfaces were investigated by aberration corrected scanning transmission electron microscopy (STEM). The atomic structure was derived directly from the high spatial resolution high angle annular dark field STEM images without recourse to image simulation. It comprises fivefold coordinated silicon and sevenfold coordinated nickel sites at the interface and shows a 2 x 1 reconstruction. The proposed structure has not been experimentally observed before but has been recently predicted theoretically by others to be energetically favored.