MICROSTRUCTURE EVOLUTION AND DEFECT INCORPORATION IN HIGHLY ORIENTED AND TEXTURED CVD DIAMOND FILMS

A series of highly oriented and textured microwave CVD diamond films, where only the deposition time was varied, was deposited on silicon wa fers ill order to follow the evolution of the microstructure and defec t content with film thickness. SEM, XRD, Raman spectroscopy, luminesce nce measurements, and ESR were applied to determine the microstructure and the defect density. It is shown that the growth of highly oriente d and textured film proceeds in two stages. The first is characterized by marked changes of the microstructure (size, orientation, and shape of the grains) which directly influence the generation of defects. Th e second stage, which begins as soon as the film surface is covered wi th {100} tiles, leads to minor changes in the microstructure and defec t incorporation. The defect-related part of the Raman spectrum has bee n decomposed into two con tributions, the D-hand which mainly responds to grain boundary defects, and the G-band which is more sensitive to volume defects. ESR measures volume defects, grain boundaries provide only a minor contribution. in this respect ESR and Raman G-band are si milar. {111} growth sectors produce defect densities which are three t o four times higher than their {100} counterparts. The thermal conduct ivity is shown to depend not only on the grain boundary density but al so on bulk defects. Optical transparency in the visible range is stron gly affected by surface roughness, however, using a new method; it has been possible to determine an absorption coefficient for the second s tage which is consistent with recently published literature data.