Engineering the structural and electronic phases of MoTe2 through W substitution

摘要

MoTe$_2$ is an exfoliable transition metal dichalcogenide (TMD) whichcrystallizes in three symmetries, the semiconducting trigonal-prismatic$2H-$phase, the semimetallic $1T^{\prime}$ monoclinic phase, and thesemimetallic orthorhombic $T_d$ structure. The $2H-$phase displays a band gapof $\sim 1$ eV making it appealing for flexible and transparentoptoelectronics. The $T_d-$phase is predicted to possess unique topologicalproperties which might lead to topologically protected non-dissipativetransport channels. Recently, it was argued that it is possible to locallyinduce phase-transformations in TMDs, through chemical doping, local heating,or electric-field to achieve ohmic contacts or to induce useful functionalitiessuch as electronic phase-change memory elements. The combination ofsemiconducting and topological elements based upon the same compound, mightproduce a new generation of high performance, low dissipation optoelectronicelements. Here, we show that it is possible to engineer the phases of MoTe$_2$through W substitution by unveiling the phase-diagram of theMo$_{1-x}$W$_x$Te$_2$ solid solution which displays a semiconducting tosemimetallic transition as a function of $x$. We find that only $\sim 8$ \% ofW stabilizes the $T_d-$phase at room temperature. Photoemission spectroscopy,indicates that this phase possesses a Fermi surface akin to that of WTe$_2$.