Thursday, October 14, 2010

US Patent 7811632 - Molecular jet growth of CNTs

Chemical vapor deposition (CVD) methods are currently seen to be the only practical way to mass produce large arrays of carbon nanotubes. However, CVD produces undesirable byproducts affecting the purity and quality of the nanotube arrays. This patent from UT-Battelle teaches an alternative approach using molecular beams which could result in practical mass production with improved purity. Claim 1 reads:   

1. A method of growing an array of essentially vertically aligned carbon nanotubes comprising the step of

impinging a beam of acetylene molecules on to a substrate to effect an acetylene incidence rate ranging from about 1.5×1018 molecules/cm2 per second to about 5.3×1018 molecules/cm2 per second to grow a continuous array of essentially vertically aligned carbon nanotubes on an entire deposition surface of the substrate at a growth temperature ranging from about 540° C. to about 740° C.,

wherein the acetylene incidence rate provides a crowding effect between adjacent carbon nanotubes during growth that results in vertical orientation of the array of essentially vertically aligned carbon nanotubes.