  Color centers in hexagonal boron nitride (hBN) have emerged as promising
candidates for single-photon emitters (SPEs) due to their bright emission
characteristics at room temperature. In contrast to mono- and few-layered hBN,
color centers in multi-layered flakes show superior emission characteristics
such as higher saturation counts and spectral stability. Here, we report a
method for determining both the axial position and three-dimensional dipole
orientation of SPEs in thick hBN flakes by tuning the photonic local density of
states using vanadium dioxide (VO2), a phase change material. Emitters under
study exhibit a strong surface-normal dipole orientation, providing some
insight on the atomic structure of hBN SPEs, deeply embedded in thick crystals.
We have optimized a hot pickup technique to reproducibly transfer flakes of hBN
from VO2 onto SiO2/Si substrate and relocated the same emitters. Our approach
serves as a practical method to systematically characterize SPEs in hBN prior
to integration in quantum photonics systems.
