# Atomic Localization of Quantum Emitters in Multilayer Hexagonal Boron Nitride

## TL;DR

This study achieves atomic-scale localization of quantum emitters in multilayer hexagonal boron nitride, revealing how fabrication methods influence emitter placement and properties, which aids in defect identification and emitter engineering.

## Contribution

It introduces a layer-by-layer etching technique for atomic localization of quantum emitters in hBN and correlates emitter position with fabrication method and lifetime, advancing defect understanding.

## Key findings

- Emitters formed by plasma are near the surface.
- Electron irradiation creates randomly distributed emitters.
- Surface proximity correlates with shorter excited state lifetime.

## Abstract

The recent discovery of single-photon emitting defects hosted by the two-dimensional wide band gap semiconductor hexagonal boron nitride (hBN) has inspired a great number of experiments. Key characteristics of these quantum emitters are their capability to operate at room temperature with a high luminosity. In spite of large theoretical and experimental research efforts, the exact nature of the emission remains unresolved. In this work we utilize layer-by-layer etching of multilayer hBN to localize the quantum emitters with atomic precision. Our results suggest the position of the emitters correlates with the fabrication method: emitters formed under plasma treatment are always in close proximity to the crystal surface, while emitters created under electron irradiation are distributed randomly throughout the entire crystal. This disparity could be traced back to the lower kinetic energy of the ions in the plasma compared to the kinetic energy of the electrons in the particle accelerator. The emitter distance to the surface also correlates with the excited state lifetime: near-surface emitters have a shorter compared to emitters deep within the crystal. Finite-difference time-domain and density functional theory simulations show that optical and electronic effects are not responsible for this difference, indicating effects such as coupling to surface defects or phonons might cause the reduced lifetime. Our results pave a way toward identification of the defect, as well as engineering the emitter properties.