Characterisation of nanocrystalline diamond coating deposited via hot filament chemical vapour deposition method with various seeding methods

Abstract

A nanocrystalline diamond bilayer has been deposited via hot filament chemical vapour deposition method. The bilayer has been produced by two different deposition parameters. The first is by limiting microcrystalline diamond growth and the second layer by pulsing additional oxygen gas into the system. The two layers become indistinguishable after the deposition ends. The pretreatment of the substrate, tungsten carbide has been varied i.e. its various seeding sizes (<0.1 μm synthetic, <0.5 μm synthetic, <0.25 μm natural, <0.5 μm natural, and <1 μm natural); with and without hammering by silicon carbide. This set up is highly similar to that of previous work however the different deposition time has caused the microcrystalline diamond layer to be nanocrystalline diamond instead. Results presented are the optical and SEM (up to 100,000x magnification) images of both planar and cross-section of the diamond layer. AFM gave topographical analysis of the diamond layer. The results show that the thickness is about 1.7 μm, top layer diamond about 100 nm in size and are indeed diamonds by XRD and Raman.