Effect of buffer thickness on single-walled carbon nanotube growth using aluminum oxide buffer layer with alcohol gas source method.
Aluminum oxide (Al2Ox) buffer layers were employed in carbon nanotube (CNT) growth using an alcohol gas source and Co catalyst. The CNT yield was strongly dependent on the Al2Ox buffer layer thickness. By optimizing the thickness of deposited Al, vertically aligned single-walled nanotubes (SWNTs) were grown on Si substrates, even under an ethanol pressure of 10(-1) Pa. Transmission electron microscopy (TEM) revealed that Co particle size was strongly dependent on Al thickness. Dense Co particles about 2-4 nm in diameter were formed at the optimal Al thickness. Surface flatness of oxide layers was relatively independent of oxide thickness, and could be easily maintained up to the onset of CNT growth. Thus, Al2Ox layers promote formation of nanosized Co particles suitable for SWNT growth, providing a significant enhancement to yield. At the higher Al thickness, the yield was reduced, which was due to the diffusion of Co particles into the Al2Ox layer. Therefore, control of Al thickness is important to obtain efficient CNT growth.
Sato
Kuniori
K
Department of Materials Science and Engineering, Meijo University, Nagoya 468-8502, Japan.
Shiraiwa
Tomoyuki
T
Maruyama
Takahiro
T
Naritsuka
Shigeya
S