Thermodynamic Evaluation and Chemical Vapor Transport of Few-Layer WTe2

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Felix Hansen - , Leibniz Institute for Solid State and Materials Research Dresden (Author)
  • Martin Wels - , Brandenburg University of Technology (Author)
  • Samuel Froeschke - , Chair of Experimental Solid State Physics, Leibniz Institute for Solid State and Materials Research Dresden (Author)
  • Alexey Popov - , Leibniz Institute for Solid State and Materials Research Dresden (Author)
  • Daniel Wolf - , Leibniz Institute for Solid State and Materials Research Dresden (Author)
  • Bernd Büchner - , Chair of Experimental Solid State Physics, Leibniz Institute for Solid State and Materials Research Dresden (Author)
  • Peer Schmidt - , Brandenburg University of Technology (Author)
  • Silke Hampel - , Leibniz Institute for Solid State and Materials Research Dresden (Author)

Abstract

Tungsten telluride WTe2is the sole candidate of a group of two-dimensional layered transition metal dichalcogenides (TMDCs) MX2with a thermodynamically stable 1T′-structure at room temperature. The binary system W/Te was audited with respect to a rational approach of planning and realization of a bottom-up synthesis of WTe2nanostructures. Thus, the parameters of the synthesis via chemical vapor transports (CVT) were derived by thermodynamic simulations of the reaction pathway according to the Calphad method. Reflecting on the peritectic melting behavior at 1020 °C, the values of ΔfHm°(298 K) = -26.5 kJ·mol-1and Sm°(298 K) = 132 J·mol-1·K-1have been obtained. According to modeling, crystal growth by short time vapor transport is reasonable under the addition of bromine or TeBr4in the temperature range between 650 and 750 °C. Experimental implementation of crystal growth of WTe2nanosheets succeeded in a temperature gradient from 725 to 675 °C on yttria-stabilized zirconia (YSZ) (111) substrates, observing the deposition of single crystal sheets of high crystallinity with thicknesses of 15-20 nm (∼20-30 layers). The high crystallinity, pristine morphology, and overall quality of the deposited nanosheets is shown by means of atomic resolution transmission electron microscopy, selected area electron diffraction (SAED), and atomic force microscopy as well as profound double-polarized Raman spectroscopy.

Details

Original languageEnglish
Pages (from-to)7341-7349
Number of pages9
JournalCrystal Growth and Design
Volume20
Issue number11
Publication statusPublished - 4 Nov 2020
Peer-reviewedYes