Temperature-Dependent Emission Spectroscopy of Quantum Emitters in Hexagonal Boron Nitride

TL;DR

This study investigates the temperature-dependent optical properties of yellow quantum emitters in hexagonal boron nitride, revealing phonon interactions and excitation mechanisms crucial for quantum technology applications.

Contribution

It extends the characterization of yellow hBN emitters to cryogenic temperatures and identifies phonon-assisted excitation pathways that enhance emission.

Findings

Identification of a bright, stable emitter at 547.5 nm

Discovery of phonon mode contribution increasing with temperature

Excitation through phonon mode boosts emission intensity by nearly 5-fold

Abstract

Color centers in hexagonal boron nitride (hBN) have attracted significant interest due to their potential applications in future optical quantum technologies. For most applications, scalable on-demand fabrication is a key requirement. Recent advances using localized electron irradiation have demonstrated near-identical emitters in the blue and yellow spectral regions. While the blue emitters have been demonstrated in cryogenic temperatures, the yellow emitters remain uncharacterized under such conditions. In this work, we therefore extended the study of yellow emitters to cryogenic temperatures. Initially, multiple spectral features were observed, prompting a systematic investigation that led to the identification of a defect emission centered around 547.5 nm with high brightness and excellent photostability. By tuning the excitation wavelength, we are able to distinguish Raman scattering peaks from the emitter emission. Further analysis of the vibronic emissions allowed us to identify an optical phonon mode, whose contribution becomes increasingly dominant at elevated temperatures. Photoluminescence excitation spectroscopy (PLE) reveals excitation through this phonon mode enhances the emission by almost 5-fold in cryogenic temperature. Temperature-dependent studies further elucidate the role of phonons in the emission process. These observations deepen our understanding of the nature of the emitters, opening new avenues for precise tuning of quantum light sources.