Molecular Bridging of Silicon Nanogaps

Ashwell G. J. , Phillips L. J. , Robinson B. J. , Urasinska-Wojcik B., Lambert C. J. , Grace I. M. , ...More

ACS NANO, vol.4, no.12, pp.7401-7406, 2010 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 4 Issue: 12
  • Publication Date: 2010
  • Doi Number: 10.1021/nn102460z
  • Journal Name: ACS NANO
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.7401-7406
  • Keywords: silicon nanogap, vertical nanogap electrode device, molecular electronics, molecular wire, self-assembled monolayer, stepwise synthesis, CLICK CHEMISTRY, WIRES, ELECTRODES, JUNCTIONS, FABRICATION, TRANSPORT, DEVICES, CONDUCTANCE, DEPOSITION, MONOLAYERS
  • Bursa Uludag University Affiliated: Yes


The highly doped electrodes of a vertical silicon nanogap device have been bridged by a 5.85 nm long molecular wire, which was synthesized in situ by grafting 4-ethynylbenzaldehyde via C-Si links to the top and bottom electrodes and thereafter by coupling an amino-terminated fluorene unit to the aldehyde groups of the activated electrode surfaces. The number of bridging molecules is constrained by relying on surface roughness to match the 5.85 nm length with an electrode gap that is nominally 1 nm wider and may be controlled by varying the reaction time: the device current increases from <= 1 pA at 1 V following the initial grafting step to 10-100 nA at 1 V when reacted for 5-15 min with the amino-terminated linker and 10 mu A when reacted for 16-53 h. It is the first time that both ends of a molecular wire have been directly grafted to silicon electrodes, and these molecule-Induced changes are reversible. The bridges detach when the device Is rinsed with dilute add solution, which breaks the imine links of the in situ formed wire and causes the current to revert to the subpicoampere leakage value of the 4-ethynylbenzaldehyde-grafted nanogap structure.