Phenylacetylene One-Dimensional Nanostructures on the Si(100)-2 × 1:H Surface

Abstract

Using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), many olefins have been shown to self-assemble on the hydrogen-passivated Si(100)-2 x 1 surface into one-dimensional nanostructures. This paper demonstrates that similar one-dimensional nanostructures can also be realized using alkynes. In particular, UHV STM, sum frequency generation (SFG), and density functional theory (DFT) are employed to study the growth mechanism and binding configuration of phenylacetylene (PA) one-dimensional nanostructures on the Si(100)-2 x 1:H surface. Molecular-resolution UHV STM images reveal the binding position and spacing of PA with respect to the underlying silicon dimer rows. Furthermore, UHV STM characterization of heteromolecular one-dimensional nanostructures of styrene and PA shows distinct electronic contrast between the two molecules, which is confirmed using simulated STM images derived from DFT and provides insight into the nature of PA binding to silicon. Additional evidence from SFG measurements corroborates the conclusion that the terminal carbon atoms of PA retain pi-conjugation following reaction to the Si(100)-2 x 1:H surface.

Mechanically activated switching of Si-based single-molecule junction as imaged with three-dimensional dynamic probe

“…Isolated DVB or DEB molecules were prepared on a H-terminated Si(001) surface. On the basis of the reaction reported in previous papers for styrene and phenylacetylene molecules on H–Si(001)3031, an adsorbed DVB (DEB) molecule is considered to be tilted from the direction normal to the Si(001) substrate surface, as shown in Fig. 2c,d.…”

“…The difference in the molecular height in the STM image observed when using DVB and DEB shown in Fig. 2e indicates a difference in the conductance of these molecules depending on the existence or nonexistence of double bonds in the junction31. A Si STM tip/single molecule/Si substrate junction was formed by the point contact method11 (Methods section).…”

“…As a possible mechanism, a cis – trans conformational change was discussed. The formation of stable covalent bonds between a molecule and semiconductor electrodes, together with the use of high-controllability semiconductor technologies, is expected to enable both basic research and the fabrication of a variety of molecular devices2425282930314041. By choosing suitable molecules, new functions originating from the flexibility of molecules, which solid-state devices themselves may not have, have the potential to be actively used for the formation of integrated functions.…”

A theoretical guide for fabricating a conductive molecular wire on a silicon surface via an in situ surface polymerization reaction

“…[1][2][3][4][5] In order to realize these applications, fabrication of one-dimensional organic molecular wires with unique electronic properties on traditional semiconducting or insulating substrates is of great importance. [8][9][10][11][12][13] Such STM control of single-molecule dynamics and molecular adsorption on surface has been attracting great attention. Currently, using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), various molecules have been shown to self-assemble and bonded on the hydrogen-passivated silicon surface into one-dimensional (1D) nanostructures.…”

“…Currently, using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), various molecules have been shown to self-assemble and bind on the hydrogen-passivated silicon surface into one-dimensional (1D) nanostructures. [8][9][10][11][12][13] Such STM control of single-molecule dynamics and molecular adsorption on the surface has been attracting great attention. 14,15 The hydrogen-passivated silicon surface is a particularly interesting substrate since UHV STM allows nanolithography and nanopatterning down to the single molecule or even the atomic level.…”