Site-specific Forest-assembly Of Single-wall Carbon Nanotubes On Electron-beam Patterned Sio_x/si Substrates

摘要

Based on electron-beam direct writing on the SiO_x/Si substrates, favorable absorption sites for ferric cations (Fe~(3+) ions) were created on the surface oxide layer. This allowed Fe~(3+)-assisted self-assembled arrays of single-wall carbon nanotube (SWNT) probes to be produced. Auger investigation indicated that the incident energetic electrons depleted oxygen, creating more dangling bonds around Si atoms at the surface of the SiO_x layer. This resulted in a distinct difference in the friction forces from unexposed regions as measured by lateral force microscopy (LFM). Atomic force microscopy (AFM) affirmed that the irradiated domains absorbed considerably more Fe~(3+) ions upon immersion into pH 2.2 aqueous FeCl_3 solution. This rendered a greater yield of FeO(OH)/FeOCl precipitates, primarily FeO(OH), upon subsequent washing with lightly basic dimethylformamide (DMF) solution. Such selective metal-functionalization established the basis for the subsequent patterned forest-assembly of SWNTs as demonstrated by resonance Raman spectroscopy.