화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.25, No.4, 1221-1226, 2007
Conducting properties of suspended carbon nanotubes grown by thermal chemical vapor deposition
Conducting properties of suspended carbon nanotubes grown by thermal chemical vapor deposition (CVD) are investigated. The thermal CVD growth is performed at a temperature about 200 degrees C lower than usual with the intention to circumvent process integration issues posed by CVD growth at higher temperatures. The growth conditions are obtained by tuning the CVD gas flows so that there are yields of devices with a small number of nanotubes bridging the metal pads. Using these growth conditions, over 70 devices with sparse bridging nanotubes are obtained at 750 degrees C. These devices are used to characterize the conducting properties. It is found that the contact resistance of 1.5-5 M Omega can be attributed to the nanotube defect densities and the resulting loose nanotube-metal contacts. Furthermore, serniconductive devices are observed. Their transfer characteristics are explained by the Schottky barrier at the nanotube-metal interface. The noise of semiconductive devices observed at large bias may be due to quantum interference between crossed nanotubes. (c) 2007 American Vacuum Society.