Straightness of Growth for Carbon Nanotube Microelectromechanical Systems

• Main Author: Moulton, Kellen S.
• Format: Others
• Published: BYU ScholarsArchive 2010
• Subjects: microelectromechanical systems; carbon nanotubes; iron catalyst thickness; Kellen Moulton; Mechanical Engineering
• Online Access: https://scholarsarchive.byu.edu/etd/2413; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=3412&context=etd

The purpose of this research is to examine the effect of iron catalyst thickness on the straightness of growth of carbon nanotube microelectromechanical systems (CNT-MEMS). One of the key benefits of CNT-MEMS is that they can potentially have very high aspect ratios. One of the challenges in attaining these high aspect ratios is maintaining device straightness; as these devices get taller, the edges tend to curve rather than grow straight vertically. Scanning electron mi- croscope images of samples grown using various iron catalyst thicknesses show that both straight growth and relatively good edge definition can be achieved using iron thicknesses between 7 and 8 nm. Below this thickness, individual CNT are well-aligned, but CNT forests are not necessarily straight. Above this thickness, the CNT forests are relatively straight, but individual CNT are not well-aligned and edge definition is very poor. Iron availability for CNT growth is also affected by a device's or feature's proximity to other regions of iron. By using an iron catalyst thickness ap- propriate for straight growth, and by adding borders of iron around features or devices, a designer can greatly improve straightness of growth for CNT-MEMS.