Oxide-mediated recovery of field-effect mobility in plasma-treated MoS ₂

Abstract

Precise tunability of electronic properties of two-dimensional (2D) nanomaterials is a key goal of current research in this field of materials science. Chemical modification of layered transition metal dichalcogenides leads to the creation of heterostructures of low-dimensional variants of these materials. In particular, the effect of oxygen-containing plasma treatment on molybdenum disulfide (MoS₂) has long been thought to be detrimental to the electrical performance of the material. We show that the mobility and conductivity of MoS₂ can be precisely controlled and improved by systematic exposure to oxygen/argon plasma and characterize the material using advanced spectroscopy and microscopy. Through complementary theoretical modeling, which confirms conductivity enhancement, we infer the role of a transient 2D substoichiometric phase of molybdenum trioxide (2D-MoO _<i>x</i> ) in modulating the electronic behavior of the material. Deduction of the beneficial role of MoO _<i>x</i> will serve to open the field to new approaches with regard to the tunability of 2D semiconductors by their low-dimensional oxides in nano-modified heterostructures.