Single Photon Emission from Deep Level Defects in Monolayer WSe2

TL;DR

This study demonstrates that applying hydrostatic pressure to monolayer WSe2 enables the observation of single photon emissions from deep level defect-bound excitons, with potential implications for quantum photonics.

Contribution

It introduces a pressure-based method to induce and study single photon emissions from deep level defects in monolayer WSe2, revealing their unique optical properties.

Findings

Discrete emission lines are pressure insensitive.

Decay time of ~10 ns for discrete emissions.

Deep level defect-bound excitons likely cause single photon emissions.

Abstract

We report an efficient method to observe single photon emissions in monolayer WSe2 by applying hydrostatic pressure. The photoluminescence peaks of typical two-dimensional (2D) excitons show a nearly identical pressure-induced blue-shift, whereas the energy of pressure-induced discrete emission lines (quantum emitters) demonstrates a pressure insensitive behavior. The decay time of these discrete line emissions is approximately 10 ns, which is at least one order longer than the lifetime of the broad localized (L) excitons. These characteristics lead to a conclusion that the excitons bound to deep level defects can be responsible for the observed single photon emissions.