  The excitonic recombinations in hexagonal boron nitride (hBN) are
investigated with spatially resolved cathodoluminescence spectroscopy in the UV
range. Cathodoluminescence images of an individual hBN crystallite reveals that
the 215 nm free excitonic line is quite homogeneously emitted along the
crystallite whereas the 220 nm and 227 nm excitonic emissions are located in
specific regions of the crystallite. Transmission electron microscopy images
show that these regions contain a high density of crystalline defects. This
suggests that both the 220 nm and 227 nm emissions are produced by the
recombination of excitons bound to structural defects.
