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Many material device applications would benefit from thin diamond coatings, but current growth techniques, such as chemical vapor deposition (CVD) or atomic layer deposition require high substrate and gas-phase temperatures that would destroy the device being coated. The development of freestanding, thin boron-doped diamond nanosheets grown on tantalum foil substrates via microwave plasma-assisted CVD is reported. These diamond sheets (measuring up to 4 × 5 mm in planar area, and 300-600 nm in thickness) are removed from the substrate using mechanical exfoliation and then transferred to other substrates, including Si/SiO 2 and graphene. The electronic properties of the resulting diamond nanosheets and their dependence on the free-standing growth, the mechanical exfoliation and transfer processes, and ultimately on their composition are characterized. To validate this, a prototypical diamond nanosheet-graphene field effect transistor-like (DNGfet) device is developed and its electronic transport properties are studied as a function of temperature. The resulting DNGfet device exhibits thermally activated transport (thermionic conductance) above 50 K. Below 50 K a transition to variable range hopping is observed. These findings demonstrate the first step towards a low-temperature diamond-based transistor. HeterojunctionsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Nucleation and growth processes of thin diamond films on fused silica optical fibres have been investigated. Fibres were coated with diamond film using microwave plasma enhanced chemical vapour deposition (mPE CVD) system. Since the growth of diamond on the fused silica glass requires high seeding density, two types of glass pre-treatment were applied: titanium dioxide (TiO 2 ) interlayer deposition and sonication in nanodiamond suspension. In the experiment, high density, thin ($20 nm) TiO 2 films were deposited using high-power impulse magnetron sputtering. Subsequently, a set of thin diamond films deposited in up to 60 min-long process was investigated. Results obtained for the two pre-treatment methods were compared. The nucleation processes were studied and compared using numerical analysis of scanning electron microscopy (SEM) images. The molecular structure of nucleated diamond was examined with micro-Raman spectroscopy. The sp 3 /sp 2 ratio was calculated using Raman spectra deconvolution method. Thickness, roughness and optical properties of the nanodiamond films in VIS-NIR wavelength range were investigated by means of spectroscopic ellipsometry. It was found that the high density TiO 2 interlayer enhances CVD diamond film nucleation processes on fused silica and increases sp 3 /sp 2 ratio of the film. The proposed growth method can be effectively applied in manufacturing of various types of optical fibre sensors. Due to high chemical and mechanical resistance of the diamond films such optical sensors are highly desired.

The undoped and B-doped polycrystalline diamond thin film was synthesized by hot filament chemical vapor deposition and microwave plasma, respectively. The structural characterization was performed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The electrical properties of synthesized diamond layer were characterized by dc-conductivity method and charge deep level transient spectroscopy.

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.