Cathodoluminescence study of diamond films grown by microwave plasma assisted chemical vapor deposition

Abstract

Diamond films, produced by microwave plasma assisted chemical vapor deposition, were studied using cathodoluminescence (CL) scanning electron microscopy and spectroscopy techniques. Luminescence intensities of the observed prominent peaks at 420, 445, and 738 nm were found to vary widely as a function of both the deposition conditions and the location in the same sample. Additional peaks and shoulders at 464, 483, 500, 514, and 532 nm were also observed in some regions of diamond films deposited using the higher (i.e., 1%) CH4/H2 concentration and the substrate temperatures below 950°C. Strong variations in CL intensities in different regions of the same sample were observed, indicating substantial variations in the distribution of defects and impurities in these diamond films. Luminescence due to the boron in a doped sample was also observed, and it was concluded that the higher CL intensity in that sample compared to other samples was due to the reduced defect densities and not due to the boron.