X-RAY STUDY OF THE INTERFACE LAYER BETWEEN LOW-TEMPERATURE DEPOSITED DIAMOND FILM AND THE SILICON SUBSTRATE

The structure of the interface layer between diamond film deposited at low temperature by microwave plasma chemical vapour deposition and the single-crystal silicon substrate was studied by X-ray diffraction (including small-angle diffraction). It was found that the interface layer for diamond films deposited at 700-degrees-C is alpha-SiC with a hexagonal unit cell of a=0.3073 nm and c=5.278 nm. At low temperatures (580-290-degrees-C), a new alpha-SiC polytype with a cell size a=0.3073 nm and c=3.77 nm, coexisted with that found at 700-degrees-C. SiO2 was also found in the interface layer, considered as the result of the increased amount of oxygen in the deposition environment necessary for the successful deposition of diamond films at low temperatures. X-ray diffraction data for diamond films deposited at 700, 580, 435, 380, and 290-degrees-C are presented. The crystal structures of alpha-SiC and SiO2, and the d-spacings of the chemically vapour deposited diamond are discussed.