Ti原子与氮掺杂金刚石(001) 界面结合强度的第一性原理研究

摘 要：金属钛原子在金刚石表面的结合强度直接影响金刚石真空介电窗口的使用性能和寿命. 本文通过基于密度泛函理论的第一性原理方法研究了Ti原子与不同氮掺杂位置的金刚石（001）界面的结合能、电荷分布和稳态几何结构. 结果表明：Ti原子与N原子取代掺杂在第二层C原子处金刚石表面的结合能比未掺杂和掺杂在第三层的结合能都高，达到-7.293 eV，使得金刚石表面形成的界面结构更加稳定，结合强度更好；通过电荷分布分析，N原子掺杂在第二层金刚石表面的Ti原子上的电荷转移最明显，对金刚石表面碳原子吸附最强，也具有更好的结合强度. 与未掺杂金刚石表面形成的Ti-C键键长相比，N掺杂在第二层和第三层C原子处金刚石表面形成的Ti-C键键长比前者分别长0.051 Å和0.042 Å，略有增加.

First-principle study on the adhesive strength of Ti atoms on N-doped diamond (001) interface

Abstract: The adhesive strength of titanium atoms on diamond surface directly affects the performance and life of diamond vacuum dielectric window. The bonding energies, charge distributions and steady-state geometries of Ti atoms on the N-doped diamond (001) interface in different doping positions are studied by the first-principle method based on density functional theory. The results show that the bonding energy (-7.293 eV) of Ti atoms on the diamond surface for N-doped in the second layer position of C atoms is higher than those for un-doped and N-doped in the third layer position of C atoms. Therefore, the interface structure formed on the diamond surface is more stable and has better adhesive strength. According to the charge distribution analysis, the charge transfer phenomenon of Ti atoms on the diamond surface of N-doped in the second layer position of C atoms is the most obvious. And it also has the strongest adsorption of carbon atoms on the diamond surface and the better adhesive strength. Compared with the Ti-C bond length formed on the surface of un-doped diamond, the Ti-C bond lengths of N-doped in the second layer and third layer positions of C atoms are slightly increased by 0.051 Å and 0.042 Å, respectively.