Effects of Tungsten Metal Coatings on Enhancing the Characteristics of Ultrananocrystalline Diamond Films

Abstract

Nucleation of diamonds on Si substrates was pronouncedly improved by pre-coating a thin tungsten film on the substrates, which is attributed to the enhancement on the formation of the W−C phase in the tungsten silicon interface. The fact that the W coating can enhance the generation of the W−C phase for the W/Si substrate is ascribed to the fast accumulation of carbon species in the W layer, which, in turn, is consequence of the limit volume for carbon inward diffusion. On the contrary, the carbon species can diffuse into the bulk W materials continuously, resulting in a markedly slower rate of accumulation for carbon species and thus delaying the formation of diamond nuclei.