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).