Publication
The unique physical properties of two-dimensional materials have attracted substantial research efforts in the last twenty years. The possibility of stacking layered materials in freely-configurable stacks, called van der Waals heterostructures, has enabled the realization of novel electronic and optoelectronic devices, as well as a plethora of fundamental discoveries in solid state physics. Optically-active layered semiconductors can be excited to create quasiparticles called excitons, consisting of electron-hole pairs that are strongly bound by Coulomb forces. Van der Waals heterostructures constitute a florid playground for the manipulation of excitons by optoelectronic means.
In this thesis, we design, fabricate and characterize excitonic devices to achieve electrical control over the emission properties, interactions, and dynamics of excitons in layered materials. By embedding van der Waals heterostructures in microcavity structures, we demonstrate the tunable cavity-coupling of spatially-indirect states, called interlayer excitons. Then, we build devices hosting exciton with tunable interlayer character thanks to layer hybridization, achieving control over their strong interactions and dynamics. We tune the transport regimes of hybrid excitons with high effective mobilities, and we demonstrate unidirectional transport of charged hybrid excitons in three-terminal field-effect devices. We proceed to employ excitonic devices to unlock high nonlinearities and strong interactions of hybrid excitons, with implications towards their use as macroscopically ordered quantum states of matter. We further employ excitons as aiding probes for the detection of materials with emergent physical phenomena. Finally, we investigate the impact of the surrounding dielectric environment on the emission and transport properties of excitons in layered materials.
These results unveil the potential of excitonic devices for future optoelectronic systems based on the long propagation of excitonic ensembles. Moreover, the broad electrical control over excitons with interlayer character holds promise towards the realization of unprecedented states of matter in van der Waals heterostructures.