PubMed Health⌕ Search

Biomedical subjects

KM Ho

Publications and source records attributed to KM Ho.

At least 19 recordsLinked to original sources
PubMed2000

Spectroscopic evidence for the tricapped trigonal prism structure of semiconductor clusters

We have obtained photoelectron spectra (PES) for silicon cluster anions with up to 20 atoms. Efficient cooling of species in the source has allowed us to resolve multiple features in the PES for all sizes studied. Spectra for an extensive set of low-energy Si(-)(n) isomers found by a global search have been simulated using density functional theory and pseudopotentials. Except for n = 12, calculations for Si(-)(n) ground states agree with the measurements. This does not hold for other plausible geometries. Hence PES data validate the tricapped trigonal prism morphologies for medium-sized Si clusters.

Journal Article↗
PubMed2000

Correlations between the scanning tunneling microscopy imaged configurations and the electronic structure on stepped Si(111)-( 7x7) surfaces

We have observed the dependence of the scanning tunneling microscopy (STM) imaged atom intensity within the (7x7) unit cell on stepped Si(111) as a function of the tunneling voltage. Pronounced differences from the corresponding atom intensity on the flat surface are observed for the contrast of atoms on the low versus the high side of the step and for the contrast between the faulted versus unfaulted subcells of the (7x7) structure. These differences can be accounted for by changes in the electronic structure within the (7x7) subcells adjacent to the step. Calculations of the local density of states and the STM images using a tight-binding method are in excellent agreement with the experimental results.

Journal Article↗