NANOTUBE ELECTROMECHANICS BEYOND CARBON: THE CASE OF WS₂

The use of 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 strain. The large sensitivity to torsion and tension suggests INT-WS₂ as promising in NEMS such as nano-gyroscopes and accelerometers.

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

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.;Teich, D.; Seifert, G.; Tenne, R.; Joselevich, E. ACS Nano 2015, Article ASAP.