Off-resonant photoluminescence spectroscopy of high-optical quality single photon emitters in GaN

TL;DR

This study investigates the optical properties of single-photon emitters in GaN, revealing large spectral shifts, the potential for electrical tuning of emission lines, and promising coherence properties for quantum technology applications.

Contribution

It provides new insights into the excitation-dependent spectral behavior and tunability of defect centers in GaN, highlighting their potential as coherent photon sources.

Findings

Spectral jumps up to 22 meV in ZPL observed

Absorption peaks mainly between 2 and 2.55 eV with variability

Achieved linewidth of 138 μeV indicating high coherence

Abstract

In this work, we analyze the relevance of excitation parameters on the emission from single-photon emitting defect centers in GaN. We investigate the absorption spectrum of different emitters by photoluminescence excitation technique at 10\,K. We report large spectral jumps (shifts up to 22\,meV) in the emitters' zero-phonon line (ZPL). The likelihood of such jumps is increased by the change in excitation energy. The shifts indicate a large built-in dipole moment of the defects and suggest a possibility to electrically tune their ZPL in a wide range. From the photoluminescence excitation studies, we observe that for majority of the emitters the absorption peaks exist between 2 and 2.55\,eV. The absorption peaks vary from emitter to emitter, and no universal absorption pattern is apparent. Finally, for selected emitters we observe significantly reduced spectral diffusion and instrument-limited linewidth of $138\,\mu eV$ (0.04\,nm).These findings show a new perspective for atomic defect GaN emitters as sources of coherent photons, shine new light on their energy level structure and show the possibility of tuning the ZPL, paving the way to fully harness their potential for applications in quantum technologies.