Cryogenic cathodoluminescence of plasma-deposited polycrystalline diamond coatings

Abstract

The cathodoluminescencespectra of microwave plasma‐deposited polycrystallinediamond films have been measured at liquid‐nitrogen temperatures over the spectral region of 230–800 nm. The diamond coatings had been deposited under several different depositiontemperatures and reactant compositions. Measurements on natural type‐IIB diamond crystals were made for comparison. The intrinsic exciton emission bands which fall in the UV just below the band edge were observed, as well as several defect and impurity bands which extend throughout the visible part of the spectrum. SEM micrographs and Raman spectra were obtained for the same set of samples used for the cathodoluminescencemeasurements. It was found that the diamond‐related cathodoluminescence features were most intense in samples whose Raman spectra exhibited the most intense cubic diamond line at 1332 cm− 1 and the least intense graphitic band at about 1500 cm− 1.