Highly Conductive Tungsten Suboxide Nanotubes

Cécile Huez (1, 2) , Maxime Berthe (2, 3) , Florence Volatron (4) , Jean-Michel Guigner (5) , Dalil Brouri (6) , Lise-Marie Chamoreau (4) , Benoît Baptiste (5) , Anna Proust (4) , Dominique Vuillaume (1)

1 NCM - IEMN - Nanostructures, nanoComponents & Molecules - IEMN
2 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
3 PCMP - IEMN - Plateforme de Caractérisation Multi-Physiques - IEMN
4 IPCM - Institut Parisien de Chimie Moléculaire
5 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
6 LRS - Laboratoire de Réactivité de Surface

We demonstrate a high electron conductivity (> 10^2 S/cm and up to 10^3 S/cm) of tungsten suboxide W18O(52.4-52.9)(or equivalently WO(2.91-2.94)) nanotubes (2 to 3 nm in diameter, ca. micrometer long). The conductivity is measured in the temperature range 120 to 300K by a four probe scanning tunneling microscope in ultra high vacuum. The nanotubes are synthesized by a low temperature and low cost solvothermal method. They selfassemble in bundles of hundreds of nanotubes forming nanowires (ca. micrometer long, few tens nm wide). We observe a large anisotropy of the conductivity with a ratio (longitudinal conductivity/perpendicular conductivity) of ca. 10^5. A large fraction of them (ca. 65 to 95%) shows a metallic like, thermal activation less, electron transport behavior. Few of them, with a lower conductivity from 10 to 10^2 S/cm, display a variable range hopping behavior. In this latter case, a hopping barrier energy of ca. 0.24 eV is inferred in agreement with the calculated energy level of the oxygen vacancy below the conduction band. This result is in agreement with a relative average concentration of oxygen vacancies of ca. 3%, for which a semiconductor to metal transition was theoretically predicted. These tungsten suboxide nanostructures are prone to a wide range of applications in nanoelectronics.

Domaines: Physique [physics]

Cécile Huez, Maxime Berthe, Florence Volatron, Jean-Michel Guigner, Dalil Brouri, et al.. Highly Conductive Tungsten Suboxide Nanotubes. Journal of Applied Physics, 2023, 134, pp.134301. ⟨10.1063/5.0170761⟩. ⟨hal-04178947v2⟩