Correlated interlayer excitons in van der Waals semiconductor heterostructures

Abstract

Interlayer excitons (IXs) are bound pairs of spatially-separated electrons and holes that occur in in type-II van der Waals heterostructures. They exhibit long lifetimes and mutual dipolar repulsion, in addition to strong interactions with unpaired electrons and holes that lead to the formation of charged IXs. To study the effect of correlations and manipulate the IXs, we design highly tunable nanodevices based on atomically thin semiconductors. Our efforts enable the study of a wealth of correlated excitonic states. In two-dimensional light-emitting diodes, we reveal the effects of defect-mediated electron localization on IXs and diode operation. We unveil the novel phenomenon of steady state cooperative electroluminescence from incoherently injected, electrically generated IXs. Lastly, we employ gate-mediated electrostatic confinement to controllably trap IXs and study their behavior at high densities, discovering novel features about the IX ionization phase diagram. These results expand our understanding of non-equilibrium phases of matter, and hold promise for creating optoelectronic devices for both future classical and quantum technologies.