Single Photon Emission from Plasma Treated 2D Hexagonal Boron Nitride

TL;DR

This study develops a plasma and thermal annealing process to create stable, oxygen-related single photon emitters in hexagonal boron nitride, advancing quantum nanophotonics applications.

Contribution

It introduces a robust two-step fabrication method that significantly increases stable quantum emitters in hBN and identifies oxygen-related defect complexes as key emitters.

Findings

Seven-fold increase in emitter concentration

Emitters are photostable at room temperature

Emission wavelengths >700 nm linked to oxygen defects

Abstract

Artificial atomic systems in solids are becoming increasingly important building blocks in quantum information processing and scalable quantum nanophotonic networks. Yet, synthesis of color centers that act as single photon emitters which are suitable for on-chip applications is still beyond reach. Here, we report a number of plasma and thermal annealing methods for the fabrication of emitters in tape-exfoliated hexagonal boron nitride (hBN) crystals. A two-step process comprised of Ar plasma etching and subsequent annealing in Ar is highly robust, and yields a seven-fold increase in the concentration of emitters in hBN. The initial plasma etching step generates emitters that suffer from blinking and bleaching, whereas the two-step process yields emitters that are photostable at room temperature and have an emission energy distribution that is red-shifted relative to that of pristine hBN. An analysis of emitters fabricated by a range of plasma and annealing treatments, combined with a theoretical investigation of point defects in hBN indicates that single photon emitters characterized by a high degree of photostability and emission wavelengths greater than ~700 nm are associated with defect complexes that contain oxygen. This is further confirmed by generating the emitters by annealing hBN in an oxidative atmosphere. Our findings advance present understanding of the structure of quantum emitter in hBN and enhance the nanofabrication toolkit that is needed to realize integrated quantum nanophotonics based on 2D materials.