Thermally induced decomposition of single-wall carbon nanotubes adsorbed on H/Si(111)

Abstract

The thermally driven reaction of carbon nanotubes with a silicon substrate is studied by photoemission spectroscopy and atomic force microscopy. Carbon nanotubes with a relatively high defect density are observed to decompose under reaction with silicon to form silicon carbide at temperatures ͑650Ϯ10°C͒ substantially lower than the analogous reaction for adsorbed C 60 . The morphology of the resultant silicon carbide islands appears to reflect the morphology of the original nanotubes, suggesting a means by which SiC nanostrutures may be produced. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1530747͔Understanding the interaction of carbon nanotubes with silicon and the resultant formation of silicon carbide at elevated temperatures is of importance due to the need to create well-defined nanotube/semiconductor heterojunctions 1 and the growing interest in fabricating silicon carbide nanorods from carbon nanotube precursors.2-4 Moreover, knowledge of the temperature at which carbide formation occurs is necessary to determine the stability of silicon/carbon nanotube interfaces which would result from integration of carbon nanotubes with silicon-based electronics. Although much effort has been directed toward understanding the interaction and thermal decomposition of C 60 on Si͑111͒ surfaces, 5-11 a closely related system, the inability to evaporate carbon nanotubes makes exploring the interaction of these species with elemental surfaces difficult.In this letter, we report an approach in which nanotubes are deposited on hydrogen passivated Si͑111͒ surfaces in an ambient atmosphere. Hydrogen is subsequently desorbed from beneath the nanotubes in an ultrahigh vacuum ͑UHV͒ environment allowing the study of the nanotube/silicon interface as a function of temperature by photoemission spectroscopy. Desorption of hydrogen from Si͑100͒-2ϫ1-H has previously been observed to occur beneath a C 60 monolayer enabling molecules to bond directly to the silicon surface. 12 We find that defective carbon nanotubes decompose on Si͑111͒ after a short anneal at 650Ϯ10°C, about 150°C ͑Refs. 6 -10͒ lower than the decomposition temperature of C 60 on Si͑111͒-7ϫ7. Ex situ atomic force microscopy ͑AFM͒ indicates that the morphology of silicon carbide islands resulting from nanotube decomposition is governed by initial nanotube geometry, suggesting a route for fabrication of nanometer scale silicon carbide structures.Photoemission experiments were undertaken at Beamline 4.1 of the Synchrotron Radiation Source, Daresbury, UK. Hydrogen passivated Si͑111͒ substrates were produced by conventional techniques and AFM images show large flat terraces, while x-ray photoelectron spectroscopy ͑XPS͒ demonstrated very low levels of residual oxide contamination. Purified single-wall carbon nanotubes ͑SWNTs͒ were supplied by the Sussex Fullerene Group and were placed in suspension by agitating small quantities in acetone in a conventional ultrasonic bath. Several droplets of the sol were cast upon a hydrogen passivated Si͑111͒ sample, and the sample...

Adsorption on Carbon Nanotubes Studied Using Polarization-Modulated Infrared Reflection−Absorption Spectroscopy

“…However, a variation of this method, in which SWNTs are deposited from a liquid suspension onto a fine W mesh, has been used elsewhere. , Method b is a workable solution; however, many reagents of interest will chemisorb readily at room temperature on Si, Ge, and their oxides as well as on SWNTs which complicates the interpretation of spectroscopic data. There is also the potential problem of reaction (e.g., SiC formation) during cleaning of the SWNTs by annealing in ultrahigh vacuum (UHV).…”

Fabrication and interfacial reaction of carbon nanotube-embedded Sn–3.5Ag solder balls for ball grid arrays

“…Moreover, CNTs are chemically inert in the range of soldering temperatures. The oxidation and decomposition temperatures of CNTs were reported to be 530°C and 650°C, respectively [24,25]. Therefore, CNT can be adopted as a reinforcing material of most commercially available solders.…”

Estudio de Nanocompuestos de Espumas de Poliuretano Reforzadas con Nanocargas en Base Carbono

“…[152] and Hunt et al [153] reported in their studies that the decomposition temperature is being reduced for high contents of amorphous carbon due to the thermal oxidative stability of the nanotubes. MWCNTs-S3 displays the higher decomposition temperature and the lowest weight percent of amorphous carbon which confirms the lower defect sites along the sidewalls of the nanotubes.…”