Exfoliation and characterization of the 1D van der Waals material tellurium*

As 1D van der Waals or weakly bonded materials, crystalline trigonal tellurium (Te) and selenium (Se) have the potential to form single atom chains with helical structures. We report ultra-thin Te flakes and nanowires obtained by mechanical exfoliation [1]. Trigonal Te single crystals were exfoliated, without tape, on oxidized silicon substrates. Atomic force spectroscopy revealed that Te nanowires with heights of 1 - 2 nm and widths below 100 nm were fabricated. Anisotropic Te flakes with a thickness of 15 nm showed ridges running along the length of the flake surfaces, unlike 2D materials that typically have smooth surfaces. A1 and E Raman modes of a 30 nm thick flake were consistent with those of bulk Te, with a slight blueshift (4 cm^-1). Polarized Raman spectroscopy was used to determine the crystal orientation of the flakes. Ongoing efforts to measure electronic transport of exfoliated Te will also be reported.
[1] H. Churchill et al. Nanoscale Research Letters 12, 488 (2017).