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-H₂mixture (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 sp³diamond phase and sp²carbon phase, both regular and amorphous, on the grain boundaries, as well as the efficiency of boron doping. The sp³/sp²ratio was calculated using the Raman spectra deconvolution method. A high refractive index (in a range of 2.0 to 2.4 at λ= 550 nm) was achieved for BDD films deposited at 700 °C. The values of extinction coefficient were below 1.4 at λ= 550 nm, indicating low absorption of the film