Investigation of excitonic recombination in single-crystal diamond with cathodoluminescence spectroscopy

Temperature-dependent cathodoluminescence (CL) measurements were performed for homoepitaxial chemical vapor deposited (CVD) diamond from 10 K to room temperature. With the increment of temperature, the unusual phenomena that the integrated intensities of free-exciton emission initially rise and then decrease, have been observed. The model based on trapping and thermal release of excitons was applied on the explanation of the unusual phenomena, and the binding energy of shallow traps in diamond at low temperatures has been obtained from the fitting experimental data. Besides, the broadening of the full width at half maximums (FWHMs) has been discussed. The exciton-phonon interactions at higher temperatures lead to the broadening of the width of the free-exciton emission.