Gas composition influence on the properties of boron-doped diamond films deposited on the fused silica

The main subject of this study are molecular structures and optical properties of boron-doped diamond films with [B]/[C] ppm ratio between 1000 and 10 000, fabricated in two molar ratios of CH4-H-2 mixture (1 % and 4 %). Boron-doped diamond (BDD) film on the fused silica was presented as a conductive coating for optical and electronic purposes. The scanning electron microscopy images showed homogenous and polycrystalline surface morphology. The Raman spectroscopy confirmed the growth of sp3 diamond phase and sp(2) carbon phase, both regular and amorphous, on the grain boundaries, as well as the efficiency of boron doping. The sp(3)/sp(2) ratio was calculated using the Raman spectra deconvolution method. A high refractive index (in a range of 2.0 to 2.4 at lambda = 550 nm) was achieved for BDD films deposited at 700 degrees C. The values of extinction coefficient were below 1.4 at lambda = 550 nm, indicating low absorption of the film.