Abstract
Tungsten ditelluride (WTe2) is a transition metal dichalcogenide (TMD) with physical and electronic properties that make it attractive for a variety of electronic applications. Although WTe2 has been studied for decades, its structure and electronic properties have only recently been correctly described. We experimentally and theoretically investigate the structure, dynamics and electronic properties of WTe2, and verify that WTe2 has its minimum energy configuration in a distorted 1T structure (Td structure), which results in metallic-like transport. Our findings unambiguously confirm the metallic nature of WTe2, introduce new information about the Raman modes of Td-WTe2, and demonstrate that Td-WTe2 is readily oxidized via environmental exposure. Finally, these findings confirm that, in its thermodynamically favored Td form, the utilization of WTe2 in electronic device architectures such as field effect transistors may need to be reevaluated.
Highlights
Te with alternating long and short distances between W atoms due to strong intermetallic bonding
To verify the stable phase and electronic properties of WTe2, we utilize Density Functional Theory (DFT) to model the crystal structures, based on atomic positions calculated from X-ray diffraction patterns of The distorted 1T structure (Td)-WTe244 and from a hypothetical 2H-WTe2 structure[11,23,26,29,47] (Fig. 1)
Since WTe2 layers are bound by weak van der Waals interaction, we performed a structural optimization using the Grimme method for van der Waals corrections[51,52], but it was observed that Local Density Approximation (LDA) yields a better description of the stacking distance, as summarized in Table S2 of the supplementary information
Summary
Te with alternating long and short distances between W atoms due to strong intermetallic bonding. The electronic band structures (c) indicate that bulk WTe2 in the 2H structure has an indirect 0.702 eV bandgap. Provide strong evidence that WTe2 has its lowest energy in a distorted 1T (Td) structure[34], called 1T’35,36. Both 2H37,38 and Td structures[35,39,40,41,42,43,44] have been reported in experimental studies of WTe2, and recent reports have focused on the extraordinary magnetoresistance[35,36,45] and thermoelectric[32,45] properties of Td-WTe2. The results presented here agree with early theory and experiments from the 1960s34,39,40,43, unlike several recent theoretical calculations and predictions of WTe2 based on a MoS2-like trigonal prismatic isomorph[23,26,29,30,31,32,46]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
