Effect of enhanced C2 growth chemistry on nanodiamond film deposition

A route to high-purity nanocrystalline diamond films from C-2 dimers and related mechanisms have been investigated by enhancing C-2 growth chemistry in Ar-rich microwave plasmas. Efficient C-2 production by direct dissociation from acetylene causes the micro- to nanocrystal transition with a low threshold Ar concentration of similar to 70% and produces films of similar to 20 nm grains with a distinct visible-Raman peak of diamond. C-2 grows nanodiamond on diamond surfaces but rarely initiates nucleation on foreign surfaces. The phase purity can be improved by increasing the dominance of nanodiamond growth from C-2 over nondiamond growth from CHx(x=0-3) and large radicals. (c) 2007 American Institute of Physics.