  The recent discovery of room temperature intrinsic single-photon emitters in
silicon nitride (SiN) provides the unique opportunity for seamless monolithic
integration of quantum light sources with the well-established SiN photonic
platform. In this work, we develop a novel approach to realize planar
waveguides made of low-autofluorescing SiN with intrinsic quantum emitters and
demonstrate the single-photon emission coupling into the waveguide mode. The
observed emission coupling from these emitters is found to be in line with
numerical simulations. The coupling of the single-photon emission to a
waveguide mode is confirmed by second-order autocorrelation measurements of
light outcoupled off the photonic chip by grating couplers. Fitting the
second-order autocorrelation histogram yields $g^{(2)}(0)=0.35\pm0.12$ without
spectral filtering or background correction with an outcoupled photon rate of
$10^4$ counts per second. This demonstrates the first successful coupling of
photons from intrinsic single-photon emitters in SiN to monolithically
integrated waveguides made of the same material. The results of our work pave
the way toward the realization of scalable, technology-ready quantum photonic
integrated circuitry efficiently interfaced with solid-state quantum emitters.
