By NanoLab Inc.
Aligned carbon nanotube arrays are grown on a number of substrates as custom orders. The arrays are synthesized in a chemical vapor deposition (CVD) system, using one of two types of CVD processes we have in house; Plasma Enhanced CVD, or Thermal-CVD. The output from these processes differ significantly in their properties. Features: PECVD - Diameter, nm: 30-150; Length, microns: 1-20; Rigidity: Freestanding (bed of nails); Site Density CNT/cm 2: 10 5 to 10 9; Substrates: Si, SiO 2, W, Mo, SS, C; Adhesion Layer: Ti or Cr, 100nm; Catalyst: Nickel; Size: up to 2" square; Patterns: Yes, lithographic; Uses: field emission devices, sensors, electrostatically actuated devices, etc. Thermal CVD - Diameter, nm: 1-2 (SWNT) 5-30 (MWNT); Length, microns: 5-500; Rigidity: Mutually Supported; Site Density CNT/cm 2: 10 10 to 10 11; Substrates: Si, SiO 2, SS, Ti, mica; Adhesion Layer: Al 2 O 3; Catalyst: Iron; Size: up to 1.25" x 4"; Patterns: Yes, lithographic; Uses: supercapacitors, electrodes, optical coatings, heat transfer, etc. PECVD Details: For PECVD arrays, the substrate (metal, glass, silicon, etc) are first coated with an adhesion layer (titanium or chromium), and then overcoated with nickel nanoparticles. The method of nickel nanoparticle deposition defines the nanotube site density. Standard density carbon nanotube forests are produced from a sputtered nickel catalyst film on the substrate, and low site-density carbon nanotube arrays are produced by electrodeposition. In the PECVD system, the carbon nanotubes grow vertically from the substrate surface, and are freestanding. The length is related to the process time, but the diameter depends primarily on the nickel particle size. In structure, PECVD aligned carbon nanotubes have multilayer graphitic sidewalls and hollow core (Fig. 1). The graphitic sidewalls contain bamboo structures (Fig. 2). All nanotube tips are capped with a single nickel nanoparticle, a result of a tip-growth mechanism of aligned carbon nanotubes (Fig. 3). Thermal CVD Details: In TCVD forests and arrays, the nanotubes are much smaller in diameter, and can grow to extreme lengths. We can readily grow either single wall or multiwall nanotubes with this process. The nanotubes are not self-supporting, and the alignment is due to crowding of neighboring nanotubes. The growth is catalyzed by an iron catalyst, typically deposited atop an alumina adhesion layer. These forests have high surface area, and can be used as is to form sensors and detectors, or drawn to form nanotube sheets or yarns. They can also be used as optical and infrared black coatings. When you order an array, please discuss your application with the sales engineer, as we have a broad experience base to draw upon to maximize the effectiveness of the products you purchase. NanoLab offers a wide variety of aligned carbon nanotube arrays. We can tailor a carbon nanotube array to your specifications, including complex patterning on many types of substrates using microscale and nanoscale lithography. Please allow three week delivery for most orders. Forests can also be transferred to other substrates if needed. phone (781) 609 2722 email an PECVD Array Specialist or a T-CVD Forest Specialist to ask questions.
