CVD法沉积金刚石薄膜中成核与生长的势垒研究

探明成核与生长的机理对于沉积高质量金刚石薄膜是十分重要的.本文采用PM3方法,计算了化学汽相沉积金刚石薄膜成核与生长阶段反应势垒.研究了对于不同反应气体(甲烷和乙炔)脱氢和增加沉积基团势垒的差异.结果说明,无论是成核阶段,还是生长阶段,脱氢势垒都小于加生长基团的势垒.然而,增加乙炔基的势垒大于增加甲基的势垒,这可能是因为乙炔分子必须打开C≡C键才能沉积到衬底表面.

Potential Barriers for CVD Diamond Films on Diamond(111) and Si(111) Substrates

A thorough understanding of the mechanism of nucleation and growth particularly at the early stage, is very important for the preparation of high quality diamond films. Using a semi-empirical quantum mechanical method (PM3), we calculated the potential barriers of reactions of chemical vapor deposition (CVD) diamond films on Si(111) substrate. Applying methane and acetylene as precursors, we investigated the abstracting of hydrogen and adding of methyl and acetyl radicals at the growth surfaces of Si(111) and diamond(111). It shows that, for both interfaces, the barriers of abstracting hydrogen are much lower than those of adding growth radicals. However, the barrier when acetyl is the precursor is higher than when methyl for both the diamond(111) and Si(111), respectively. It is suggested that only when the C≡C bond of acetylene molecular breaking can it be added to the growth surfaces.