Anisotropic transport in 1T′ monolayer MoS2 and its metal interfaces

Abstract

The investigation of crystallographic orientation dependent carrier transport in a material could lead to novel electronic devices and circuit applications. Although the out-of-plane carrier transport in layered transition metal dichalcogenides (TMDs) is expected to differ from its normal counterpart, in-plane anisotropy is not so common in such materials. The symmetric honeycomb structure of a semiconducting 2H phase MoS₂ crystal limits the in-plane anisotropy. However such possibility in a distorted 1T phase i.e., the 1T′ phase of the MoS₂ crystal has not yet been explored. Using first principles based quantum transport calculations we demonstrate that, due to the clusterization of “Mo” atoms in 1T′ MoS₂, the transmission along the zigzag direction is significantly higher than that in the armchair direction. Since the metallic 1T′ phase finds application in realizing low resistive metal–MoS₂ contacts, we further extend this study to the 1T′ MoS₂ interface with gold and palladium by developing atomistic models for the optimized metal–1T′ MoS₂ edge contact geometries. Analysing the transmission spectra and electronic conductance values we show that the metal–zigzag 1T′ MoS₂ interfaces provide best case results, irrespective of the choice of metal. Moreover, we observe that edge contact geometries with the gold electrodes offer lesser resistances, compared to those with palladium electrodes. Our findings could pave the way for designing high performance phase-engineered MoS₂ based electron devices.