Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

We compare the charge transport characteristics of heavy doped p- and n-Si-alkyl chain/Hg junctions. Photoelectron spectroscopy (UPS, IPES and XPS) results for the molecule-Si band alignment at equilibrium show the Fermi level to LUMO energy difference to be much smaller than the corresponding Fermi level to HOMO one. This result supports the conclusion we reach, based on negative differential resistance in an analogous semiconductor-inorganic insulator/metal junction, that for both p- and n-type junctions the energy difference between the Fermi level and LUMO, i.e., electron tunneling, controls charge transport. The Fermi level-LUMO energy difference, experimentally determined by IPES, agrees with the non-resonant tunneling barrier height deduced from the exponential length-attenuation of the current

Pd-Pt and Fe-Ni nanoparticles formed by covalent molecular assembly in supercritical carbon dioxide

10.1016/j.jcis.2007.11.034Journal of Colloid and Interface Science3201333-340JCIS

Dendrimer-based nanostructured ultrathin films formed by covalent molecular assembly in supercritical carbon dioxide

too lon

Catalyst-Free Functionalization for Versatile Modification of Nonoxidized Silicon Structures

Here we report on a simple, catalyst-free route for obtaining highly versatile subsequent functionalization on Si nanowires and Si(111) substrates. The versatility of this approach allows subsequent functionalization not only for organic species but also for inorganic (nanomaterial) species. The method has the advantage of controlling, the density of reactive cross-linkers without affecting the stability of the Si samples and without having metallic (or catalyst) residues on the surface. This method also allows formation Of monolayers with a variety of termination groups and is expected to open up a. wide range of,opportunities for producing stable molecule based (opto)electronic and (bio)sensing devices Immobilization of inorganic nanomaterial on the Si, samples offers advanced opportunities in molecular switches, (bio)sensors, molecular Scale memory, and Si based nanoelectronic devices

Stable organic mono layers on oxide-free silicon/germanium in a supercritical medium: A new route to molecular electronics

Oxide-free Si and Ge surfaces have been passivated and modified with organic molecules by forming covalent bonds between the surfaces and reactive end groups of linear alkanes and aromatic species using single-step deposition in supercritical carbon dioxide (SCCO2). The process is suitable for large-scale manufacturing due to short processing times, simplicity, and high resistance to oxidation. It also allows the formation of monolayers with varying reactive terminal groups, thus enabling formation of nanostructures engineered at the molecular level. Ballistic electron emission microscopy (BEEM) spectra performed on the organic monolayer on oxide-free silicon capped by a thin gold layer reveals for the first time an increase in transmission of the ballistic current through the interface of up to three times compared to a control device, in contrast to similar studies reported in the literature suggestive of oxide-free passivation in SCCO2. The SCCO2 process combined with the preliminary BEEM results opens up new avenues for interface engineering, leading to molecular electronic devices