Electrical and electromechanical properties of WS2 nanotubes

Roi Levi, Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel

The use of various nanostructures such as nanotubes and 2D sheets in electrical and electromechanical devices is the subject of intensive research in recent years. In particular, the electronic properties of inorganic compounds such as the dichlcogenides sparked the research of their incorporation into nano-electro-mechanical systems (NEMS). WS₂ nanotubes (INT-WS₂) have been shown to exhibit superior mechanical properties and interesting stick-slip mechanical phenomena¹ and thus are a natural candidate for electro-mechanical devices.

  We show here that INT-WS₂ possess significant field-effect mobility and surprisingly high current carrying capacity². We further present the first demonstration of a significant electro-mechanical response in pure inorganic nanotubes³. The INT-WS₂ exhibited a highly repeatable increase of the conductivity in response to strain and/or torsion. These results are in qualitative agreement with the theoretical calculations presented here for torsion and previous theoretical predictions for strain. The large sensitivity to torsion and tension suggests INT-WS₂ as promising in NEMS such as nano-gyroscopes and accelerometers.

Figure 1 - (a) Atomic force microscope image (AFM) of a WS₂ nanotube-based torsional nano-electro-mechanical system (NEMS). Inset - INT-WS₂-NEMS schematic and the AFM tip used to perform the torsion. (b) INT-WS₂-NEMS electrical response to torsion - change in conductivity vs. torsion angle.

References

(1) Nagapriya, K. S.; Goldbart, O.; Kaplan-Ashiri, I.; Seifert, G.; Tenne, R.; Joselevich, E. Physical Review Letters 2008, 101, 195501.

(2) Levi, R.; Bitton, O.; Leitus, G.; Tenne, R.; Joselevich, E. Nano Letters 2013, 13, 3736-3741.

(3) Levi, R.; Garel, J.; Seifert, G.; Tenne, R.; Joselevich, E. In preparation 2015.