Carbon nanotube tips for a scanning probe microscope: their fabrication and properties

We report a well controlled method to make carbon nanotube tips for a scann ing probe microscope (SPM). A multiwalled carbon nanotube, which is purifie d by the electrophoresis, is transferred onto a conventional Si tip for a S PM using a scanning electron microscope (SEM) equipped with two independent specimen stages. The nanotube is fixed on the Si tip by electron beam depo sition of carbon. A force curve measurement of nanotubes using the nanotube tips in the SEM reveals that Young's modulus of a nanotube of 20 nm diamet er is 1.1 TPa and the fixing of nanotubes by the carbon deposit is effectiv e. The nanotube tips are used to image plasmid deoxyribonucleic acids on mi ca by tapping mode. The average resolution by using the nanotube tips is ab out two times higher than that by the best Si tips.