Comparative study of band-A cathodoluminescence and Raman spectroscopy in CVD diamond films

A set of diamond films was grown by microwave plasma enhanced chemical vapo ur deposition using a CO2-CH4 gas mixture. Film morphology, preferential or ientation and crystal quality were systematically changed by varying the CW , concentration and substrate temperature in the ranges 47-52% and 750-850 degrees C, respectively. The resulting films were characterised by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and cathodolumi nescence (CL). The crystalline quality of the films, as assessed by Raman s pectroscopy, increases at lower substrate temperatures (T-s = 750 degrees C ) and when moving from (110) towards (100) texturing. Independently of the substrate temperature, a strong decrease of the band-A cathodoluminescence at 435 nm is found as the him preferential orientation goes from (110) to ( 100). A clear correlation between the width of the diamond Raman line and t he band-A emission is observed, giving insight into the nature of this band . In particular, this result is consistent with the attribution of band-A C L to the presence of dislocations. (C) 1999 Published by Elsevier Science S .A. All rights reserved.