基于第一性原理的CVD金刚石涂层表面氧原子作用分析

Analysis of the effect of oxygen atoms on the surface of CVD diamond coatings based on first principles

采用第一性原理方法研究了氧原子在CVD金刚石涂层表面吸附形成的两种氧掺杂结构的差异及脱附CO的难易程度.仿真计算结果表明:氧原子在金刚石表面顶位和桥位吸附形成C=O羰结构和C-O-C醚结构,改变与其直接成键的局部金刚石结构;C-O-C结构吸附能比C=O结构大,其结构更加稳定;C=O结构断键脱附形成CO的能垒比C-O-C结构更低,CVD金刚石涂层表面脱附CO主要是以C=O断键形成;氢终止表面能够增强碳原子之间成键,提高C=O脱附的能垒,而氧终止表面作用相反,降低脱附能垒.

The first principles method was used to study the difference between two oxygen-doped structures formed by the adsorption of oxygen atoms on the surface of the CVD diamond coating and the difficulty of desorption of CO.The simulation calculation results show that the oxygen atoms are adsorbed on the top and bridge positions of the diamond surface to form a C=O carbonyl structure and a C-O-C ether structure,changing the local diamond structure directly bonded to it.The adsorption energy of the C-O-C structure is bigger than that of the C=O structure,and its structure is more stable.The energy barrier of CO formed by bond breaking and desorption of C=O structure is lower than that of C-O-C structure.CVD diamond coating surface desorption CO is mainly formed by C=O bond breaking.Hydrogen termination surface can enhance the bond formation of carbon atoms and increases the energy barrier of C=O desorption,while oxygen terminates the surface effect on the contrary,lowering the energy barrier of desorption.