Growth of diamond films on silicon from an oxygen-acetylene flame

Clear diamond films have been deposited on silicon substrates by a tilted oxygen-acetylene flame operating at one atmosphere pressure in air. High quality diamond films are formed by well-defined diamond crystallites in the octahedral and cubooctahedral shapes as well as of intermediate forms. Raman spectra of the flame deposited diamond display a peak very close to that for natural diamond with little or no broad band corresponding to graphitic bonding as well as a peak corresponding to the underlying silicon substrate. This shows that the diamond is transparent to visible light and that there are little or no interfacial materials other than silicon and diamond. Using an O₂: C₂ H₂ volume ratio around 0.98 high quality diamond films thicker than 10 μm have been grown on silicon in less than 30 min by an oxygen-acetylene flame that is aimed at the silicon substrate at about 70°with respect to the direction normal to the silicon surface.