High Temperature Quantum Emission from Covalently Functionalized van der Waals Heterostructures

TL;DR

This paper demonstrates that covalent functionalization and heterostructure engineering of WSe2 monolayers significantly increase the temperature at which high-purity single photon emission can be observed, surpassing 90 K.

Contribution

It introduces a novel combination of molecular functionalization and heterostructure design to enhance quantum emission stability at higher temperatures in 2D materials.

Findings

High purity SPE persists above 90 K

Functionalization maintains SPE integrity up to 115 K

Temperature range for quantum emission is tripled

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are attractive nanomaterials for quantum information applications due to single photon emission (SPE) from atomic defects, primarily tungsten diselenide (WSe2) monolayers. Defect and strain engineering techniques have been developed to yield high purity, deterministically positioned SPE in WSe2. However, a major challenge in application of these techniques is the low temperature required to observe defect-bound TMD exciton emission, typically limiting SPE to T<30 K. SPE at higher temperatures either loses purity or requires integration into complex devices such as optical cavities. Here, 2D heterostructure engineering and molecular functionalization are combined to achieve high purity (>90%) SPE in strained WSe2 persisting to over T=90 K. Covalent diazonium functionalization of graphite in a layered WSe2/graphite heterostructure maintains high purity up to T=90 K and single-photon source integrity up to T=115 K. This method preserves the best qualities of SPE from WSe2 while increasing working temperature to more than three times the typical range. This work demonstrates the versatility of surface functionalization and heterostructure design to synergistically improve the properties of quantum emission and offers new insights into the phenomenon of SPE from 2D materials.