Effect of Gas Pressure on Nanocrystalline Diamond FilmsPrepared by Electron-Assisted Chemical Vapour Deposition

Abstract

With use of electron-assisted chemical vapour deposition (EACVD)technology, nanocrystalline diamond films are successfully deposited onan α-SiC single phase ceramics substrate by means of reduction of thereactive gas pressure. The structure and surface morphology of thedeposited films are characterized by Raman spectroscopy, x-raydiffraction (XRD), field emission scanning electron microscopy (FE-SEM)and atomic force microscopy (AFM). The results examined by FE-SEM andAFM show that when the gas pressure was reduced to 0.5–1 kPa, thesurface grain size and surface roughness of the diamond film aredecreased greatly to 18–32 nm and 34–58 nm respectively. Thegrain sizes estimated from full with at half maximum of (111) XRD peakby the Scherrer formula are 6–28 nm. However, too high secondarynucleation rate may result in pores and defects in the deposited films.Only at suitable gas pressure (1 kPa) to deposit films can we obtaindensification and better quality nanocrystalline films.