Effect of thermal oxidation on the topography of the crystals. (a–d) AFM profile of an 60 × 60 μm2 portion of the microcrystalline film (a, c) before and (b, d) after oxidation. The depth of the features increases by about 1.5 μm. (e, f) SEM images of (e) microcrystalline diamond surface, and (f) after thermal oxidation showing the transformation from flat crystals to pyramid-like structures with submicron-size tops. With permission from Applied Surface Science, Copyright 2013.