Ir/SiC界面结合力、稳定性和电子结构的第一性原理研究

First-Principles Study on Adhesion,Stability,and Electronic Structure of Ir/SiC Interfaces

基于密度泛函理论(DFT)第一性原理研究了Ir(111)/SiC(111)界面。在考虑不同堆垛位置和表面封端的基础上,共研究了6种不同的界面构型。结果表明:具有9层原子层的Ir(111)表面构型表现体相材料的特征,而12层原子层的SiC(111)表面构型能体现体相SiC的性能。粘附功和界面能结果表明,C封端顶位堆垛(C-TS)和Si封端中心位堆垛(Si-CS)界面构型具有最大的粘附功,分别为6.35和6.23 J/m^(2),是最稳定的构型;弛豫后的界面能分别为0.07和0.10 J/m^(2)。电子结构分析表明:C-TS界面处具有离子特性,而Si-CS界面处具有共价键特性。C-TS和Si-CS界面的结合强度和稳定性归因于Ir-d与C-p,Si-p轨道之间的杂化。与C-TS界面相比,Si-CS界面第2层原子与界面Ir原子的相互作用更大。

The Ir(111)/SiC(111)interfaces were investigated by first-principles study based on density functional theory(DFT).Considering different stacking sites and terminations,six different interfaces were studied.The results show that an Ir(111)slab with 9 atom layers exhibits bulk-like interior characteristic,while a 12-atom-layer SiC(111)slab represents the properties of bulk SiC.Adhesion and interfacial energy results show that the C-terminated top-site(C-TS)and Si-terminated center-site(Si-CS)interfaces are highly stable with the highest work of adhesion of 6.35 and 6.23 J/m^(2),and the smallest interfacial energy of 0.07 and 0.10 J/m^(2)after relaxation,respectively.Electronic structure analysis reveals that the C-TS interface has the ionic characteristics,while the Si-CS interface exhibits covalent bond characteristics.The bonding strength and stability of C-TS and Si-CS interfaces are attributed to the hybridization between Ir-d and C-p,Si-p orbits.Compared with the C-TS interface,sub-interfacial atoms have more interaction with Ir atoms in Si-CS interface.