CATHODOLUMINESCENCE SPECTROSCOPY OF SYNTHETIC DIAMOND FILMS

A set of diamond films was grown by microwave chemical vapor depositio n (MWCVD) using a CH4-H-2 gas mixture. Structural and crystallographic defects were induced in the samples either by choosing a relatively h igh substrate temperature, T-s = 950 degrees C, or by intentional cont amination. In addition, different preferential orientations were obtai ned by appropriate changes to the CH4 concentration in the gas mixture . The resulting films were characterized by scanning electron microsco py (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Room tempera ture and liquid nitrogen temperature cathodoluminescence (CL) were inv estigated in the 200-800 nm wavelength range. A clear correlation with the growth conditions of the so-called band-A emission (435 nm) and o f some sharp spectral features was observed. An explanation of this ef fect is given in terms of crystal defects which are induced by the gro wth process. (C) 1997 Elsevier Science S.A.