化学汽相沉积金刚石生长表面氢原子覆盖率的研究

A STUDY ON THE SURFACE COVERAGE OF THE CHEMICAL VAPOR DEPOSITED DIAMOND BY HYDROGEN ATOMS

化学汽相沉积金刚石生长表面的悬挂键是其赖以成核和生长的表面活性格点。但是两个以上悬挂键聚集在一起时,局部表面能量比较高,悬挂键之间容易发生重构,形成π键或者dimer键,成为石墨结构的生长基样点。因此,金刚石的生长主要依赖于表面上的单个悬挂键集团和气相中的碳氢活性基团。石墨则主要依赖于表面上的多个悬挂键组成的集团,石墨的生长可以被表面附近活性氢原子的刻蚀作用所抑制。对表面悬挂键的微观分布状态的统计计算结果表明,(111)和(100)生长表面的氢原子覆盖率分别为0.86单层(ML)和0.80ML时,单位表面积上的单个悬挂键团密度最高,金刚石的生长速率为最大极值。对于同时显露(111)和(100)面的多晶金刚石膜生长表面,则表面的氢原子最佳覆盖率应为0.83ML。

The optimum surface coverage of diamond by hydrogen during chemical vapor depositon processes has been studied. It is assumed that the reduced chemical reaction of the singlet state of the surface dangling-bonds is different from that of the dangling-bonds-clusters in which the dangling-bonds may combine each other at the surface and form non-diamond structrures. The singlet states of the surface dangling bonds may be the main templets contributed to the diamond growth. It has been observed that the optimum surface coverage is 0.86 monolayer (ML)for { 111} oriented surface , and 0. 80 ML for {100} oriented surface for diamond growth, and it may be the maximum growth rate at a definite concentration of hydrocarbon fragments at the surface.