The spectacular progress in controlling the electronic properties of graphene has triggered research in alternative atomically thin two-dimensional crystals. Monolayers (ML) of transitionmetal dichalcogenides such as MoS₂ have emerged as very promising nanostructures for optical and electronic applications for mainly two reasons.

First, the indirect bulk semiconductor MoS₂ becomes direct when thinned to 1ML, resulting in efficient optical absorption and emission. Second, inversion symmetry breaking (usually absent in graphene) together with the large spin-orbit interaction leads to a coupling of carrier spin and k-space valley physics, i.e., the circular polarization (σ+ or σ−) of the absorbed or emitted photon can be directly associated with selective carrier excitation in one of the two nonequivalent k valleys (K+ or K−, respectively). We have investigated the optical and valley properties for both neutral and charged excitons in transition metal dichalcogenide monolayers. In this talk I will give an overview of the physical properties of 2D semiconductors based on Transition Metal Dichalcogenides (MoS₂, MoSe₂, WS2, WSe₂, MoWSe₂) : band structure, exciton effects, spin and valley dynamics…


Wednesday, January 13, 2016, 12:00. ICFO’s Seminar Room

Hosted by Prof. Adrian Bachtold