氢、氧原子刻蚀CVD金刚石涂层石墨相的机理研究

Mechanism of hydrogen and oxygen etching graphite phase in CVD diamond coatings

采用第一性原理分子模拟计算方法对氢、氧原子刻蚀石墨相的过程进行分子动力学仿真,分析了2种原子在石墨相上的吸附过程及刻蚀反应的反应热和反应能垒。结果表明:氧原子在石墨相表面的吸附能强于氢原子吸附能,同时氧原子的化学反应活性大于氢原子的,更容易在石墨结构表面发生电子转移反应;氢原子促使石墨相表面的C—C键断裂需要两步反应,而氧原子则只需要一步反应,氢原子刻蚀石墨相的反应能垒比氧原子的高,所需能量更多。同时,通入含氧气源可以有效降低CVD金刚石涂层的沉积温度,提高金刚石涂层的质量。

In order to study the etching mechanism of hydrogen and oxygen atoms on the graphite phase in CVD diamond coatings,molecular dynamics simulation on the etching process was performed using first-principle molecular simulation calculation method.The adsorption process of either atom on graphite phase and the reaction heat and energy barrier of etching reaction were analyzed.The results show that the adsorption energy of oxygen atoms on the surface of the graphite phase is stronger than that of hydrogen atoms.At the same time,the chemical reactivity of oxygen atoms is stronger than that of hydrogen atoms.It is more easier to form an electron transfer reaction with the surface of the graphite structure.It takes 2 steps to break the C—C bond on the graphite phase surface,while the oxygen atom requires only one step.It means that hydrogen atoms etching the graphite phase have higher reaction energy barrier and require more energy.The oxygen-containing gas source can effectively reduce the deposition temperature of the CVD diamond coating and improve its quality.