Effect of microwave power and nitrogen addition on the formation of {100} faceted diamond from microcrystalline to nanocrystalline

In this work, we report {100} multi-faceted diamond from large grained micro- to nano-crystalline obtained by microwave plasma chemical vapor deposition (MPCVD). The diamond samples were grown using different microwave power 2000 and 3200 W with a small amount of nitrogen and oxygen addition into conventional methane and hydrogen plasma in a 5 kW MPCVD reactor. Scanning electron microscopy (SEM), micro-Raman spectroscopy and X-ray diffraction (XRD) were used to characterize the morphology, crystalline quality and orientation or texture of the diamond samples. SEM micrographs clearly evidence various diamonds of distinct morphologies consisting of smooth square {100} facets from micrometer or nanometer size. Especially novel morphology, large {100} faceted nanocrystalline diamond balls of high growth rate 17.0 μm/h were obtained. The effect of microwave power and temperature and the role of nitrogen addition on diamond growth rate and the formation of different types of {100} faceted diamond from micro- to nanocrystalline is discussed. These results shed light into the specific growth mechanism of CVD diamond upon nitrogen perturbation.

► Large smooth {100} facet-terminated nanocrystalline diamond balls were achieved.
► <100> oriented nanocrystalline diamond film was achieved using low power 2000 W.
► A very large grained {100} textured diamond film was produced at high power 3200 W.