First principles investigation of quantum emission from hBN defects

TL;DR

This study uses density-functional theory to identify and analyze specific defects in hexagonal boron nitride that could serve as stable single-photon emitters at room temperature, aligning well with experimental observations.

Contribution

It provides a detailed first-principles analysis of defect structures in hBN, pinpointing the CBVN defect as a promising quantum emitter candidate.

Findings

CBVN defect has a Huang-Rhys factor of 1.66 matching experiments.

Calculated photoluminescence line shape reproduces key experimental features.

CBVN defect identified as a potential stable single-photon emitter.

Abstract

Hexagonal boron nitride (hBN) has recently emerged as a fascinating platform for room-temperature quantum photonics due to the discovery of robust visible light single-photon emitters. In order to utilize these emitters, it is necessary to have a clear understanding of their atomic structure and the associated excitation processes that give rise to this single photon emission. Here we perform density-functional theory (DFT) and constrained DFT calculations for a range of hBN point defects in order to identify potential emission candidates. By applying a number of criteria on the electronic structure of the ground state and the atomic structure of the excited states of the considered defects, and then calculating the Huang-Rhys (HR) factor, we find that the CBVN defect, in which a carbon atom substitutes a boron atom and the opposite nitrogen atom is removed, is a potential emission source with a HR factor of 1.66, in good agreement with the experimental HR factor. We calculate the photoluminescence (PL) line shape for this defect and find that it reproduces a number of key features in the the experimental PL lineshape.