Transition-metal dichalcogenide heterostructures as a robust, tunable platform for studying exciton-exciton interactions

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The goal of this project is to establish transition-metal dichalcogenide heterostructures (TMDC-HS) as a robust, tunable platform for studying interlayer excitons and their interactions. Due to their bosonic nature, excitons have a rich phase diagram as a function of temperature and density. Interlayer excitons in TMDC-HS offer several advantages over more established, GaAs-based heterostructures, including significantly larger exciton binding energies, the novel valley degree of freedom and design parameters such as the relative orientation of adjacent monolayers. However, they also present challenges which stem from their sensitivity to the environment, leading to pronounced inhomogeneous broadening that is much larger than in high-quality GaAs heterostructures. We propose to optimize the fabrication of TMDC-HS using encapsulation in other two-dimensional materials (e.g. hexagonal Boron Nitride), and to integrate nanostructured electrodes which define electrostatic traps for exciton confinement. We shall utilize various optical spectroscopy techniques to characterize these novel structures and to investigate the dynamics of interlayer excitons in the regime of high densities and low temperatures.