M. Aghajanian, A. A. Mostofi and J. Lischner, Tuning electronic properties of transition-metal dichalcogenides via defect charge, Scientific Reports 8, 13611 (2018)

Since the experimental realisation and characterisation of monolayer graphene in 2004, there has been a focussed interest on so-called two-dimensional materials. One class of such materials is the transition metal dichalcogenides (TMDs). Monolayer TMDs, such as MoS₂, are interesting because, unlike graphene, they are semiconductors and have potential technological applications in field-effect transistors, photovoltaics, and sensing.

The properties of monolayer TMDs are highly tunable via the addition of defects and absorbates, such as charged impurities. Understanding and controlling the effect of such impurities is essential for the rational design of defect-engineered TMDCs.

In a paper published in Scientific Reports, we use a multi-scale theory and simulation approach that combines first-principles and tight-binding simulations to calculate impurity wave functions and binding energies for both donor and acceptor adsorbed impurity atoms on MoS₂ as function of the impurity charge. One of our main findings is that it is possible to control the ordering of the most strongly bound impurity state by varying the impurity charge, which has potentially important consequences for optical properties.

This work was part of Martik Aghajanian’s PhD in the Centre for Doctoral Training in Theory and Simulation of Materials. Martik is supervised by Johannes Lischner and Arash Mostofi.