TiN(111)/DLC界面粘附功和电子结构的第一性原理研究

A first-principles study of adhesion and electronic structure at TiN(111)/DLC interface

摘要:

利用基于密度泛函理论的第一性原理,采用平面波赝势方法,研究了TiN(111)/DLC界面的粘附功和电子结构,阐明了TiN过渡层改善金属基体和DLC薄膜结合性能的内在机理。根据TiN(111)面不同的表面终端(Ti终端和N终端)和界面原子配位类型(顶位、中心位和孔穴位),构建和计算了6种可能的TiN(111)/DLC界面理论构型。结果表明：当TiN(111)以Ti原子为终端时,中心位堆垛界面(Ti-center)的粘附功最大；当TiN以N原子为终端时,顶位堆垛界面(N-top)为最稳定的界面模型,弛豫后的粘附功为8.281 J/m_²。差分电荷密度、分态密度、Mulliken布居数的计算结果均表明：Ti-center界面Ti原子和C原子形成的Ti-C键包含共价性和离子性；N-top界面处C原子和N原子形成C-N共价键。相比之下,N-top模型更有可能在TiN/DLC界面中出现。

Abstract:

The effect of adhesion and electronic structure of TiN(111)/DLC interface is studied by the first-principles plane wave pseudopotential method within the density functional theory, and the inherent properties of the TiN transition layer to improve the adhesion performance of the metal substrate and DLC film were clarified. According to different surface terminations (Ti terminations and N terminations) of TiN(111) and the atomic coordination types of the interface (top, center and hollow), six possible interfaces models of TiN(111)/DLC have been constructed and calculated. The results show that Ti-center interface has the maximum adhesion energy；When TiN is terminated by N atom, the N-top interface is the most stable interface model, and the relaxed adhesion energy is 8.281 J/m_². The calculation results of the electron density, the partial density of states and Mulliken overlap population all suggest that Ti-C bond formed at Ti-center interface contains covalent and ionic properties, while N atom and C atom at N-top interface are mainly C-N covalent bond. In contrast, the N-top model is more likely to appear in the TiN/DLC interface.