Characterizations of microwave plasma CVD grown polycrystalline diamond coatings for advanced technological applications

Abstract

Polycrystalline diamond (PCD) coatings ranging from few microns to several hundred microns thickness have been grown by 915MHz microwave plasma reactor with 9000W power. The coatings were deposited on 100mm diameter silicon (Si) substrate from few hours to several days of continuous runs. PCD coatings were made freestanding by wet chemical etching technique. The deposited PCDs were evaluated by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), Raman spectroscopy,X-ray photoelectron spectroscopy (XPS) for physical characterization and compared with authors? earlier work. Refractive index of 2.41 was obtained at 633 nm wavelength and a maximum of 6.6 W?cm-1K-1 value for thermal conductivity could be achieved with the grown coatings. The values are well above the existing non-diamond heat spreading substrates, which makes the grown PCDs as candidates for heat spreaders in different technological applications. High refractive in- dex along with translucent nature of the white freestanding PCDs, make them potential candidate for optical windows.