Optical and electrical properties of boron doped diamond thin conductive films deposited on fused silica glass substrates

Abstract

This paper presents boron-doped diamond (BDD) film as a conductive coating for optical and electronic purposes. Seeding and growth processes of thin diamond films on fused silica have been investigated. Growth processes of thin diamond films on fused silica were investigated at various boron doping level and methane admixture. Two step pre-treatment procedure of fused silica substrate was applied to achieve high seeding density. First, the substrates undergo the hydrogen plasma treatment then spin-coating seeding using a dispersion consisting of detonation nanodiamond in dimethyl sulfoxide with polyvinyl alcohol was applied. Such an approach results in seeding density of 2×1010cm−2. The scanning electron microscopy images showed homogenous, continuous and polycrystalline surface morphology with minimal grain size of 200nm for highly boron doped films. The sp3/sp2 ratio was calculated using Raman spectra deconvolution method. A high refractive index (range of 2.0–2.4 @550nm) was achieved for BDD films deposited at 500°C. The values of extinction coefficient were below 0.1 at λ=550nm, indicating low absorption of the film. The fabricated BDD thin films displayed resistivity below 48Ohm cm and transmittance over 60% in the visible wavelength range.