Quantum control of interlayer excitons in atomically thin semiconductor heterostructures - Nadine Leisgang

Two-dimensional materials and their heterostructures provide a highly tunable platform for many-body interactions and strongly correlated phenomena, including Mott insulators, generalized Wigner crystals and excitonic insulators. Of particular interest are atomically thin transition metal dichalcogenides (TMDs), such as MoS₂, MoSe₂ and WSe₂. They strongly interact with light to form excitons – electrons and holes bound by Coulomb attraction – which remain stable up to room temperature. The reduced dimensionality together with the relatively large effective mass and low kinetic energy of the charge carriers yield strong interactions between the individual electrons and excitons in the system. In addition, new excitonic species can be formed when combining two or more TMD monolayers, where the electrons and holes are separated between the individual layers – so-called interlayer excitons (IXs). The ability to engineer and control the properties of the thin semiconductors by external means makes these systems a versatile platform for rich exciton and electron physics and unique opto-electronic applications.
Here, we investigate strongly correlated phenomena in two varieties of TMD bilayers – homobilayer MoS₂ [1–3] and heterobilayer MoSe₂/WSe₂ [4–5]. These host IXs with large out-of-plane electric dipoles. We study the quantum-confined Stark effect of the IXs in these systems, as well as their interaction with additional charges.