  The ability of hexagonal boron nitride to host quantum emitters in the form
of deep-level color centers makes it an important material for quantum photonic
applications. This work utilizes a monolithic circular Bragg grating device to
enhance the collection of single photons with 436 nm wavelength emitted from
quantum emitters in hexagonal boron nitride. We observe a 6- fold increase in
collected intensity for a single photon emitter coupled to a device compared to
an uncoupled emitter, and show exceptional spectral stability at cryogenic
temperature. The devices were fabricated using a number of etching methods,
beyond standard fluorine-based reactive ion etching, and the quantum emitters
were created using a site-specific electron beam irradiation technique. Our
work demonstrates the potential of monolithically-integrated systems for
deterministically-placed quantum emitters using a variety of fabrication
options.
