The recently discovered molybdenum-based nanowires [1, 2] are easy to synthesize and disperse, and they exhibit a variety of properties in which they are superior to other one-dimensional materials, such as large Young moduli and small shear moduli, properties that make it useful as ultra-low-friction lubricants. The conductivity of these nanowires is about 0.04 Sm-1 and have a critical current density of 104 A cm-2 [3].
Here, we study the electrical properties of these nanowires correlated with transmission electron characterizations using a TEM in-situ probing method. This technique utilizes a tiny scanning tunnelling microscope (STM) incorporated with a side-entry TEM holder [4,5]. The STM tip is used for electrical probing of individual nanowires while the TEM is used for characterisation. At low bias voltage we find conductivity values similar to previously reported ones. However, with increased voltages (5-50 V), and the corresponding increase in current density, the conductivity increases and the TEM images shows a kind of annealing behaviour where kinks and disorder in the nanowires are disappearing. The electron diffraction patterns are also changing above the annealing current-voltage settings, indicating a change in the structure of the nanowires. The measured critical current densities of 106 Acm-2 in these bundles of single nanowires are 2-3 orders of magnitude higher than found in ref [3] and slightly above that found for multi walled carbon nanotubes (CNT). This means that the molybdenum based nanowires might be a rival to CNTs in the electronics area as well.
[1] M. Remskar, A. Mrzel, Z. Skraba, A. Jesih, M. Ceh, J. Demsar, P. Stadelman, F. Levy and D. Mihailovic, Science 292, 479 (2001)
[2] D. Vrbanic, M. Remskar, A. Jesih, A. Mrzel, P. Umek, M. Ponikvar, B. Jancar, A. Meden, B. Novosel, S. Pejovnik, P. Venturini, J.C. Coleman, and D. Mihailovic, Nanotechnology, 15 (2004) 635
[3] B. Bercic, U. Pirnat, P. Kusar, D. Dvorsek, D. Mihailovic, D. Vengust, B. Podobnik, Appl. Phys. Lett. 88 (2006) 173103
[4] K. Svensson, Y. Jompol, H. Olin, and E. Olsson, Rev. Sci. Instr. 74 (2003) 4945
[5] Nanofactory Instruments (www.nanofactory.com)
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