Spin-allowed quantum emission from strain confinement in monolayer semiconductors

Here we demonstrate quantum emitter behavior from strained monolayer MoSe₂. Exciton confinement has been achieved using strain associated with causing the monolayer to conform to a nanoscale indentation prepared in the substrate. By sufficiently reducing the lateral scale of the confinement, we have achieved single quantum emitter behavior, with the A exciton feature showing a drop in linewidth to below 0.2 meV at cryogenic temperatures, in an emission 70-meV redshifted from the bulk A exciton feature of the unstrained monolayer. The quantum emitter characteristics of these confined excitons has been demonstrated directly by g(2) measurements. Unlike recent demonstrations of quantum emitters in monolayer WSe₂, the exciton involved for our MoSe₂ samples has a spin aligned configuration. This was demonstrated by Zeeman measurements indicating a g factor of 4, and was also reflected in the relatively short, 0.2 ns measured photoluminescence lifetimes. Our approach has the potential for creating spin-allowed quantum emitters that can be arbitrarily located laterally and tuned by the engineered strain properties.