The effect of deposition parameters on the morphology of micron diamond powders synthesized by HFCVD method

• Millions of micron diamonds are deposited simultaneously on a substrate by HFCVD.
• The diamond seeds are dispersed evenly onto the substrate using a novel technique.
• Deposition parameters are optimized for growing well-faceted micron diamonds.

The micron well-faceted diamond powders have attracted an increasing attention in the polishing filed, owing to improve the surface finish of components using the powders. In the present work, the hot filament chemical vapor deposition (HFCVD) technique is employed for synthesizing such diamond powders. A great many of micron diamonds are grown simultaneously but independently onto a large-area substrate. First, a novel seeding method, spraying the diamond seeds suspension toward the substrate using a spin coater machine, is proposed, with which the seeds with a controlled density are distributed evenly onto the substrate. Also, the method is more suitable for the fabrication of the micron isolated diamonds, compared with other nucleation initiation methods, such as the scratching pre-treatment and electrical biasing on substrates. Afterwards, a systematic investigation is under taken into the effects of deposition parameters on the basic growth characteristics of CVD micron diamonds, and on the inhibition of films growth. Furthermore, the reactive pressure, substrate temperature, carbon concentration, and growth duration are determined to be 4500 Pa, 850 °C, 1.3–1.4%, 60–90 min, respectively. Eventually, under the preferred deposition conditions, approximately 15 million cube-octahedral crystals with the mean size of 2–3 μm are deposited simultaneously on the 1000 mm2 substrate.