Due to their unique properties, carbon nanotubes (CNTs [1]) and carbon nanofibers (CNFs) are thought to be an ideal probe for scanning probe microscopes (SPMs). Much effort has been devoted to fabricate CNT- or CNF-based SPM probes since the discovery of CNTs. Nevertheless, the batch fabrication of CNT- or CNF-tipped probes is still quite challenging because of several unsolved difficulties in conventional fabrication methods, such as the manual attachment of single CNTs or chemical vapor deposition growth of CNTs onto SPM chips.
In the previous paper, we demonstrated that the batch-growth of linear-shaped single CNFs onto commercially available Si cantilevers (9 chips / batch) [2] using a newly developed Ar+ ion-irradiation method [3]. In the present work, the mechanical and electric properties of ion-induced CNF probes thus small-scale batch-fabricated were investigated.
The dynamic mode force-curve measurements revealed the better flexibility of CNF and CNT probes compared with Si probes. After the durability test of the repeated scans (50 times) on Ti surfaces, the change in the image resolution for CNF probes was small enough compared with that for Si probes. Thus, the mechanical properties of the ion-induced CNF probes were confirmed to be almost comparable to those attained for high quality CNT probes.
In the I-V measurements, Si probes showed a typical diode characteristic, while CNF probes displayed a metallic characteristic. Surprisingly, no change in resistance was detected for the CNF probes even at the current as large as micoampere. In the scanning spreading resistance microscopy (SSRM) measurements, due to the small radial curvature and high aspect ratio of CNF probes, high quality imaging with a better sensitivity in the surface roughness was achieved by CNF probes, compared with SSRM images attained by commonly used electro-conductive diamond probes. Thus, it was believed that the CNF probes were quite promising as practical SPM probes.
[1] S. Iijima: Nature 354 (1991) 56.
[2] M.Tanemura, M.Kitazawa, J.Tanaka, T.Okita, R.Ohta, L.Miao, S.Tanemura: Jpn. J. Appl. Phys. 45 (2006) 2004.
[3] M. Tanemura, et al., Appl. Phys. Lett., 84 (2004). 3831, 86 (2005) 113107.
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