Broadening mechanisms of quantum emitters in CVD and exfoliated hexagonal Boron nitride at temperatures ranging 4K-300K on conductive and insulating substrates

Defect based single photon emitters in hexagonal boron nitride exhibit promising photophysical properties as a room temperature source of quantum light, however spectral diffusion poses challenges towards utilizing these emitters in quantum applications which require indistinguishable photons. Here we study photoluminescence of hBN single emitters via variable temperature (4K-300K) spectroscopy and compare exfoliated, chemically vapor deposition (CVD) grown and bulk hBN crystals. Furthermore, we propose a method to reduce spectral diffusion by using a conductive substrate ITO. Our method can decrease the inhomogeneous linewidth of hBN single emitters by 45%. Our findings are a step forward towards indistinguishable photon sources at room temperature based on hBN color centers.