P11: Electronic structure and charge transport in defective and doped TMDCs

Supervision:Agnieszka Kuc, Bálint Aradi

Motivation and state of the art: Electronic properties of semiconducting transition-metal chalcogenides (TMCs) can be easily tuned in a controlled manner by external modulators, e.g. tensile strain or electric field. However, it might also be strongly affected by structural defects or impurities, which are not easily controllable. The carrier mobility in mechanically exfoliated MoS2 may drop by up to two orders of magnitude if produced by chemical vapour deposition. Therefore, it is extremely important to understand the destructive or constructive influence of structural defects and impurities on the intrinsic properties of TMCs.

Own work: We have studied electronic properties of perfect TMCs, their electronic band gaps, spin-orbit splitting, and electronic transport. We have investigated how these properties are affected by applied electric field or tensile strain (Stark and Rashba effects). We have carried out preliminary studies on the influence of defects on properties of MoS2 monolayers.

Aims and work plan: We will investigate the effect of defects (grain boundaries, vacancies, line defects) and impurities (atomic substitutions) on the electronic structure of 2D TMCs. The changes in the intrinsic properties, e.g. spin-orbit splitting and electronic transport, due to the structural imperfections will be studied. Defective structures will be subject to the mechanical deformations and electric field in order to investigate if these modulators are still advantageous in the control of the electronic properties. We will employ density-functional based methods and our non-equilibrium Green’s function codes extended for spin-polarized coherent transport. Collaborations are planned with P6 and P7 (interfaces), P10 (transport calculations) and P12 (effect of defects in devices).