In this report control over the growth direction of horizontally aligned of carbon nanotubes (CNTs) by an ion beam surface treatment is investigated. The CNTs are grown by chemical vapor deposition (CVD) using ethanol as the carbon source. The ethanol gets decomposed by the cobalt catalyst. The catalyst is deposited as cobalt-oxide by atomic layer deposition (ALD), which allows for accurate control of the layer thickness. In order to get consistent growth of CNTs the growth conditions, like temperature and sample position, have been optimized and single walled carbon nanotubes (SWNTs) have been grown.Molybdenum-oxide has been added to the cobalt catalyst by using an ALD process. SWNTs were grown as well, however, the addition of more molybdenum-oxide showed a detrimental effect on the CNT density. This is possibly due to phase segregation of the metals. Using different anneal approaches to prevent phase segregation were not successful and did not improve the growth of CNTs on samples with more molybdenum-oxide.Using a low energy oblique ion beam treatment of the sample surface before growth of CNTs resulted in CNT growth aligned along the ion beam direction. This alignment was not perfect, but shows that an ion beam treatment has promise to be used as an alignment technique for CNTs. The effects of the ion beam acceleration, angle of incidence and exposure time on the alignment have been investigated, but showed no clear improvements.
|Date of Award||29 Feb 2016|
|Supervisor||Ageeth A. Bol (Supervisor 1) & N.F.W. Thissen (Supervisor 2)|