| AVS 56th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Monday Sessions |
| Session NS+BI-MoA |
| Session: | Nanowires and Nanoparticles II |
| Presenter: | H. Yabutani, Santa Clara University |
| Authors: | H. Yabutani, Santa Clara University T. Yamada, Santa Clara University T. Saito, Santa Clara University C. Yang, Santa Clara University |
| Correspondent: | Click to Email |
To assess their potential for interconnect applications, the interplay between electrical and thermal transport in carbon nanofibers (CNFs) under high-current stress is examined. Current-voltage measurement results obtained during each stress cycle reveal temperature-dependent behavior of CNF resistance, the analysis of which is the subject of this paper.
To minimize the contact resistance between gold electrode and CNF, tungsten is deposited on each electrode using focused ion beam [1]. For each test device, we apply stressing current progressively, i.e., in the first cycle, a small current is applied for three minutes, and in the second cycle, a slightly larger current is applied for another three minutes, etc. Using this scheme, we obtained a decrease in average resistance with increasing stressing current for each stress cycle. In ref. [2], we presented a heat transport model that takes into account Joule heat generation, dissipation, and diffusion during current stressing. In this model, the CNF temperature along its length was determined as a function of stressing current. Since the increase in temperature originates from Joule heating, and since we established that current stressing has little effect on the total resistance at ambient temperature prior to breakdown [1], this result suggests that the reversible resistance change due to Joule heating is a result of change in bulk CNF properties at elevated temperatures.
The mechanism for CNF bulk resistance decrease with temperature was discussed in the context of transport in disordered media [3]. Our CNF devices have impurities and/or lattice defects, which often serve to trap carriers. Thermal energy releases these carriers from the trap centers, giving rise to lower resistance. Thus transport is controlled by thermal activation of these trapped carriers and their subsequent re-trapping as the temperature is lowered. The same mechanism would account for the observed decrease in resistance as the temperature increases with increasing stressing current due to Joule heating.
[1] T. Saito, T. Yamada, D. Fabris, H. Kitsuki, P. Wilhite, M. Suzuki, and C. Y. Yang, Appl. Phys. Lett. 93, 102108 (2008).
[2] T. Yamada, T. Saito, D. Fabris, and C. Y. Yang, IEEE Electron Device Lett. 30, 469-471 (2009).
[3] Q. Ngo, T. Yamada, M. Suzuki, Y. Ominami, A. M. Cassell, J. Li, M. Meyyappan, and C.Y. Yang, IEEE Transactions on Nanotechnology 6, 688-695 (2007).