Direct Fabrication of Functional Ultrathin Single-Crystal Nanowires from Quasi-One-Dimensional van der Waals Crystals

Micromechanical exfoliation of two-dimensional (2D) van der Waals materials has triggered an explosive interest in 2D material research. The extension of this idea to 1D van der Waals materials, possibly opening a new arena for 1D material research, has not yet been realized. In this paper, we demonstrate that 1D nanowire with sizes as small as six molecular ribbons, can be readily achieved in the Ta₂(Pd or Pt)₃Se₈ system by simple micromechanical exfoliation. Exfoliated Ta₂Pd₃Se₈ nanowires are n-type semiconductors, whereas isostructural Ta₂Pt₃Se₈ nanowires are p-type semiconductors. Both types of nanowires show excellent electrical switching performance as the channel material for a field-effect transistor. Low-temperature transport measurement reveals a defect level inherent to Ta₂Pd₃Se₈ nanowires, which enables the observed electrical switching behavior at high temperature (above 140 K). A functional logic gate consisting of both n-type Ta₂Pd₃Se₈ and p-type Ta₂Pt₃Se₈ field-effect transistors has also been successfully achieved. By taking advantage of the high crystal quality derived from the parent van der Waals bulk compound, our findings about the exfoliated Ta₂(Pd or Pt)₃Se₈ nanowires demonstrate a new pathway to access single-crystal 1D nanostructures for the study of their fundamental properties and the exploration of their applications in electronics, optoelectronics, and energy harvesting.