Novel electromechanical properties of Carbon nanotube (CNT) enable their great potential in many fields. However, correlating the property and the structure of the same CNT is still challenging. Here, using our newly developed in situ platform inside a scanning electron microscope (SEM) [1], we study the strain-induced bandgap change and electric induced vibration of CNT and correlate them with the atomic structure of the CNT. Individual CNTs are placed across the pre-fabricated source and drain electrodes on the platform by nanomanipulation [2]. The CNT is stretched precisely by changing the distance between the source and drain electrodes [3] and its electrical property is measured at each strain. On one hand, the strain-induced bandgap change, dEgap/dε, is extracted from the measured transfer curves of the CNT devices at different axial strain [4]. On the other hand, the theoretical predicted dEgap/dε of the same CNTs are calculated [5] using the diameter and chirality of the CNTs determined through transmission electron microscopy [2]. For the first time, the experimental obtained dEgap/dε agrees quantitatively with the theoretical prediction. We also find that dEgap/dε of double-wall CNT and triple-wall CNT are mainly determined by their outer wall chirality. Electric induced vibration of CNT is studied using a resonator structure similar to that reported previously [6]. The resonance frequency of our CNT resonators is tuned not only transversally by a gate voltage, but also by the axial strain of the CNT. The resonance frequency of a single-wall CNT resonator is tuned by more than 20 times when the axial strain of the CNT is only increased from nearly zero to 2%. The transversal gate-tuning ability is weaker than the axial-tuning ability, and decreases with increasing the axial strain. The obtained relationship among the resonance frequency, the gate voltage and the axial strain will allow for the design of novel CNT resonators.

References:

[1] Z. Y. Ning, M.Q. Fu, T. W. Shi, Y. Guo, S. Gao, X. L. Wei, Q. Chen: Nanotech., in press.

[2] X. L. Wei, Q. Chen, L. M. Peng, R. L. Cui, Y. Li: Ultramicroscopy, 110 (2010), 182.

[3] Z. Y. Ning, M.Q. Fu, T. W. Shi, Y. Guo, S. Gao, X. L. Wei, Q. Chen: Nano Lett., 14 (2014), 1221.

[4] E. D. Minot, Y. Yaish, V. Sazonova, J.-Y. Park, M. Brink, P. L. McEuen: Phys. Rev. Lett., 90 (2003), 156401.

[5] L. Yang, J. Han: Phys. Rev. Lett., 85 (2000), 154.

[6] V. Sazonova, Y. Yaish, H. Ustunel, D. Roundy, T. A. Arias, P. L. McEuen: Nature, 431 (2004), 284.

Qing Chen

Peking University

Appearances