  Adapting optical microscopy methods for nanoscale characterization of defects
in two-dimensional (2D) materials is a vital step for photonic on-chip devices.
To increase the analysis throughput, waveguide-based on-chip imaging platforms
have been recently developed. Their inherent disadvantage, however, is the
necessity to transfer the 2D material from the growth substrate to the imaging
chip which introduces contamination, potentially altering the characterization
results. Here we present a unique approach to circumvent these shortfalls by
directly growing a widely-used 2D material (hexagonal boron nitride, hBN) on
silicon nitride chips, and optically characterizing the defects in the intact
as-grown material. We compare the direct growth approach to the standard wet
transfer method, and confirm the clear advantages of the direct growth. While
demonstrated with hBN in the current work, the method is easily extendable to
other 2D materials.
