248 Biosensors Based on Nanomaterials and Nanodevices
10.2.1 NCD Definition
Films with large grain size (i.e., high surface roughness), low diamond purity, or large
stress are undesirable for device integration and performance. In the 1990s, a new class of
diamond material, nanocrystalline diamond (NCD) emerged (Butler and Sumant 2008). It
is essentially a thin version of conventional MCD and its surface is composed of the facets
of the largest crystals that survived during the nucleation process. Such a Van De Drift
growth mechanism leads to NCD surface roughness proportional to the lm thickness.
With its grain size, surface roughness, and thickness, all in the range of 10s–100s of nano-
meters, it became easy to microfabricate and integra ...