Lateral Manipulation of Single‐Walled Carbon Nanotubes on H‐Passivated Si(100) Surfaces with an Ultrahigh‐Vacuum Scanning Tunneling Microscope

Abstract

Ultrahigh-vacuum (UHV) scanning tunneling microscopy (STM) can be used for the manipulation of individual atoms and molecules into complex arrangements for sensitive electrical and structural characterization. However, the systematic UHV STM manipulation of single-walled carbon nanotubes (SWNTs), high-aspect-ratio molecular wires derived from graphene that exist in both semiconducting and metallic forms, has yet to be reported. In this work, we demonstrate the room-temperature lateral manipulation of approximately 1-nm-diameter SWNTs on UHV-prepared, hydrogen-passivated Si(100) surfaces. We show the reproducible actuation of SWNTs having lengths as small as 13 nm, along with the partial division of a two-tube bundle. Moreover, UHV STM desorption of H at the SWNT/Si interface is introduced as a means of locally strengthening the interaction between the tube and the surface. The UHV STM manipulation scheme described here is potentially extensible to the orientational control of SWNTs interfaced with atomically clean semiconducting surfaces, such as InAs(110), GaAs(110), and unpassivated Si(100), for which first-principles calculations based on density functional theory have been reported recently in the literature.

Preferential Orientation of a Chiral Semiconducting Carbon Nanotube on the Locally Depassivated Si(100)‐2×1:H Surface Identified by Scanning Tunneling Microscopy

“…With the DCT method, predominantly isolated (rather than bundled) SWNTs having lengths in the range of tens of nanometers to several micrometers can be deposited in UHV at a concentration suitable for STM (≈1–10 tubes μm −2 ) and with minimal contamination. We have demonstrated previously the room‐temperature lateral manipulation of DCT‐deposited SWNTs on hydrogen‐passivated Si(100) surfaces with the UHV STM 11. Moreover, the band alignments between s‐SWNTs and both n‐doped and p‐doped H‐Si(100) were obtained by STM spectroscopy and ab initio calculations 12.…”

“…Although the SWNT was intercepted by a 10‐nm‐wide stripe of Si dangling bonds (bounded by the dotted vertical lines), stable imaging of the SWNT could still not be achieved. We have shown previously that this form of patterning also removes the hydrogen passivation directly beneath the nanotube 11. The vertical arrow on the right side of the image illustrates how the SWNT is seemingly pulled along the slow‐scan direction of the STM scan due to attractive interactions with the tip.…”

“…One approach to locally strengthen the interaction between the SWNT and the H‐Si(100) substrate is the electron‐stimulated desorption of H at the SWNT/H‐Si(100) interface,11 a form of STM nanolithography20 demonstrated in the 46 nm×18 nm STM image shown in Figure 1 b. Although the SWNT was intercepted by a 10‐nm‐wide stripe of Si dangling bonds (bounded by the dotted vertical lines), stable imaging of the SWNT could still not be achieved.…”

Temperature-Dependent Two-State Dynamics of Individual Cooperatively Rearranging Regions on a Glass Surface

“…The surface composition analyzed by X-ray photoelectron spectroscopy was very similar to the bulk. Oxidefree samples were transferred directly from the sputtering chamber into a home-built ultra-high vacuum scanning tunneling microscope (P <1.3 × 10 -9 Pa) [10], and scanned with electrochemically etched tungsten probe tips. To observe samples at the highest resolution, 1-2 V sample bias and 10 pA tunneling currents were employed.…”

Direct Imaging of Two-State Dynamics on the Amorphous Silicon Surface

“…The evaporation was done in a UHV preparation chamber attached to the STM chamber to avoid any surface oxide formation. STM movies of the glass surface were recorded on a home-built STM using the design from [14]. The base pressure was below 10 -10 torr.…”