Structural Phase Stability Control of Monolayer MoTe2 with Adsorbed Atoms and Molecules

We study the adsorption of some common atoms and molecules onto monolayer MoTe2 and the potential for adsorption to induce a structural phase change between the semiconducting 2H-based and metallic 1T'-based crystal structures of the monolayer. Using density functional theory with spin orbit and van der Waals energy contributions, we determined energetically favorable adsorption positions and orientations on the two crystalline phases of monolayer MoTe2. We then obtained the formation energies for these adsorption reactions and found that atomic adsorption generally favors 1T' metallic phases while molecular adsorption favors semiconducting 2H phases. The phase sensitivity of this material is due to a relatively small energy difference, approximately 31 meV per MoTe2 formula unit. We further find that the monolayer alloy MoxW1-xTe2 can exhibit some degree of molecular selectivity in phase changes, potentially providing the basis for molecular sensing applications.