Understanding bound excitons in 2D monolayer semiconductors with nano-optical imaging and spectroscopy

Bound excitons in 2D semiconductors are of interest as potential qubits as well as single-photon emitters for quantum computing and information applications. But our limited understanding of these states inhibits overcoming several challenges that they pose for integration into practical technological applications. One such issue is the suppression of bound excitons at temperatures above ~150 K. Employing a suite of time-resolved and nano-optical spectroscopy studies, we find that the thermally-activated process suppresses their formation and develop a nano-optical architectural motif to reverse this suppression and activate the states at room-temperature. Furthermore, using nano-optical imaging and spectroscopy, distinct bound exciton states are optically imaged within strain-induced potentials at resolutions down to 20 nm. This nanoscale resolution allows us to measure the extent to which these states are localized as well as identify how nanoscale strain controls their excited-state properties. From these studies, we can begin to envision how to use nano-optical antennas to integrate patterns of bound exciton states in two-dimensional monolayer semiconductors for model optoelectronic and room-temperature quantum devices.