Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

Abstract

In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp 3 / sp 2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV-vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass-nanocrystalline interface, and thus potentially increases transmittance of the optical system.

Opto-Electrochemical Sensing Device Based on Long-Period Grating Coated with Boron-Doped Diamond Thin Film

“…The obtained diamond overlay is continuous and homogenous along the fiber (Fig. 2(b)), in agreement with previously obtained results on the fused glass slides [23,24]. Average crystallite size is between 100 and 200 nm (Fig.…”

Linear antenna microwave chemical vapour deposition of diamond films on long-period fiber gratings for bio-sensing applications

“…In our previous works, high power sonication seeding was applied to different suspensions (water/DMSO) in order to obtain diamond films on optical fibers [13]. We have observed that high power seeding can induce the erosion/cavitation of optical fibers.…”

Nanodiamonds: From Synthesis and Purification to Deposition Techniques, Hybrids Fabrication and Applications

“…It can be applied to various substrates [97][98][99], on large surfaces, up to eight inches [100,101]. Contrary to BEN, 3D substrates like silicon tips [102,103] or silica optical fibers [104] can be homogeneously coated [105]. The main challenge is the improvement of diamond films adhesion [20,93].…”