Strain-tunable Single Photon Sources in WSe2 Monolayers

TL;DR

This paper demonstrates a device that uses strain engineering via a piezoelectric substrate to reversibly tune the emission energy of single photon sources in WSe2 monolayers, with implications for quantum technologies.

Contribution

It introduces a hybrid 2D-semiconductor-piezoelectric device enabling reversible, strain-based tuning of single photon emission energies in WSe2 monolayers, revealing strain-dependent effects on quantum emitters.

Findings

Strain can tune single photon energies up to 18 meV.

The energy shift depends on the emitter and strain sign.

Finite element simulations explain strain effects on emitters.

Abstract

The appearance of single photon sources in atomically thin semiconductors holds great promises for the development of a flexible and ultra-compact quantum technology, in which elastic strain engineering can be used to tailor their emission properties. Here, we show a compact and hybrid 2D-semiconductor-piezoelectric device that allows for controlling the energy of single photons emitted by quantum emitters localized in wrinkled WSe2 monolayers. We demonstrate that strain fields exerted by the piezoelectric device can be used to tune the energy of localized excitons in WSe2 up to 18 meV in a reversible manner, while leaving the single photon purity unaffected over a wide range. Interestingly, we find that the magnitude and in particular the sign of the energy shift as a function of stress is emitter dependent. With the help of finite element simulations we suggest a simple model that explains our experimental observations and, furthermore, discloses that the type of strain (tensile or compressive) experienced by the quantum emitters strongly depends on their localization across the wrinkles. Our findings are of strong relevance for the practical implementation of single photon devices based on two-dimensional materials as well as for understanding the effects of strain on their emission properties.