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Multiwalled carbon nanotubes (MWNTs) were synthesized using a chemical vapor deposition floating feed method in a vertical reactor. Effects of the preparation variables on the average diameter of carbon nanotubes were systematically examined using the fractional factorial design (FFD), path of the steepest ascent, and central composite design (CCD) coupled with the response surface methodology. From...
Polarization dependence of the optical absorption properties of SWNTs is presented and investigated in detail for the energy range 0.5–6eV. We found that the absorption peaks in the UV region at approximately 4.5 and 5.25eV exhibit remarkable and different dependencies on the morphology of the SWNT film, or equivalently, on the incident light polarization relative to the SWNT axis. An analytical pathway...
A novel and simple growth mark method was developed to make marks during the growth process of carbon nanotube arrays. These marks can be read out under scanning electron microscope or optical microscope. Based on this method, the growth rates at different temperatures and under different acetylene partial pressures were measured, from which the activation energy and the order of reaction were determined...
We report the successful optimization of single-wall carbon nanotube (SWCNT) synthesis by catalytic chemical vapor deposition (CCVD) on FeMo/MgO catalyst using acetylene as carbon source. Taking a starting parameter set from the literature we optimized seven (catalyst composition, catalyst amount, reaction temperature, reaction time, preheating time, C 2 H 2 volumetric flow rate, inert...
We report the transient response of room temperature pulses generated from alpha particles from a chemical vapor deposition (CVD) polycrystalline diamond detector. For transient signals dominated by electron transport only prompt pulse shapes were observed with an average rise time of 160ns limited by the preamplifier rise time. For transient signals dominated by hole transport significant slow components...
High density, well-aligned carbon nanotubes (CNTs) were prepared by thermally decomposing acetylene at 700°C with the help of Ni–Cr alloy as catalyst in a thermal chemical vapor deposition system. The density and alignment of CNTs were characterized by scanning electron microscope (SEM). It was found that the density of the CNTs could be remarkably increased and the alignment could be improved with...
The influence of applied electric field (E av ) and emission current (I FE ) on the configuration of conical layers carbon nanotubes (CLNTs) grown by CVD on the edge of Ni foil has been investigated. TEM profile imaging revealed a high concentration of nanotubes near the foil edge surface, whereas on the nanotube layers’ outer surfaces single, non-oriented nanotubes with open ends...
A novel synthesis of carbon nanotubes for field-emitter arrays with a uniform field emission current is reported. Microwave plasma chemical vapor deposition and a unique structure of a sandwich catalyst stack are used to grow vertically aligned carbon nanotubes with a high density, uniform length and diameter. After being etched in a H 2 /N 2 -microwave plasma, the overall field emission...
The remarkable properties of carbon nanotubes (CNTs) make them attractive for microelectronic applications, especially for interconnects and nanoscale devices. In this paper, we describe a microelectronics compatible process for growing high-aspect-ratio CNT arrays with application to vertical electrical interconnects. A lift-off process was used to pattern catalyst (Al 2 O 3 /Fe)...
Single walled nanotubes have been synthesized by chemical vapor deposition from camphor, camphor analogs (camphorquinone, norcamphor, norbornane, camphene, fenchone), and various other precursors (menthone, 2-decanone, benzene, methane). The high temperature conditions (865°C) and Fe/Mo alumina catalyst used in the syntheses are archetypal conditions for the production of single walled carbon nanotubes...
We discuss growth of high-quality carbon nanotube (CNT) films on bare and microstructured silicon substrates by atmospheric pressure thermal chemical vapor deposition (CVD), from a Mo/Fe/Al 2 O 3 catalyst film deposited by entirely electron beam evaporation. High-density films having a tangled morphology and a Raman G/D ratio of at least 20 are grown over a temperature range of 750–900°C...
Activated carbon modified by HNO 3 was used as the support during the production of TiO 2 by metal organic chemical vapor deposition (MOCVD). The HNO 3 modification increased mesopores surface area of activated carbon indicating the size of pores increased. The concentration of surface oxygen bearing groups on the HNO 3 modified activated carbon was much higher than...
The interaction between carbon nanotubes (CNTs) and substrate plays an important role in the process of field emission. A double-barrier model is adopted to analyze the difference of field emission for various CNT films. Result shows that the width of interface barrier determines the emission performance. For CNTs on titanium, the best emission performance is attributed to the removal of interlayer...
Large quantities of CN x /carbon nanotube intramolecular junctions were successfully synthesized on a silicon substrate via the chemical vapor deposition method by pyrolysis of ferrocene and melamine. The nanotubes have two apparently different sections, one made of carbon with an empty hollow cylinder structure, and the other made of carbon nitride with a bamboo-like structure. Three- and...
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