Electronic properties of assembled islands of hydrogen-saturated silicon clusters on Si(111)-(7×7) surfaces studied by scanning tunneling spectroscopy
Joint Research Center for Atom Technology (JRCAT), Angstrom Technology Partnership, 1-1-1
Higashi, Tsukuba, Ibaraki 305-0046, Japan
2 JRCAT, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan
Published online: 15 September 2001
We present results of scanning tunneling spectroscopy (STS) measurements of hydrogen-saturated silicon clusters islands formed on Si(111)-() surfaces. Nanometer-size islands of Si6H12 with a height of 0.2-4 nm were assembled with a scanning tunneling microscope (STM) using a tip-to-sample voltage larger than 3 V. STS spectra of Si6H12 cluster islands show characteristic peaks originating in resonance tunneling through discrete states of the clusters. The peak positions change little with island height, while the peak width shows a tendency of narrowing for the tall islands. The peak narrowing is interpreted as increase of lifetime of electron trapped at the cluster states. The lifetime was as short as 10-13 s resulting from interaction with the dangling bonds of surface atoms, which prevents charge accumulation at the cluster islands.
PACS: 61.16.Ch – Scanning probe microscopy: scanning tunneling, atomic force, scanning optical, magnetic force, etc. / 61.46.+w – Nanoscale materials clusters, nanoparticles, nanotubes and nanocrystals / 36.40.Cg – Electronic and magnetic properties of clusters / 73.50.-h – Electronic transport phenomena in thin films
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001