Microstructure and electronic property of pristine and thermal barrier layers TiN/AlN/ZrB₂ buffered 4H-SiC/W interface from first principles study

Improving the mechanical behavior and understanding underlying mechanism of ceramics/metal systems play a fundamental role in engineering the novel film/coating systems and evaluating the device performance comprised of heterointerfaces. Here, the representative heterointerface 4H-SiC/W system is adopted for investigating interfacial structure and electronic property of the pristine interface and thermal barrier layers buffered one. The pristine 4H-SiC/W interface is established by first principles calculations on energetic and electronic structure of a total 6 candidate interfacial models. The results show that the preferred interfacial structure (i.e., that having the largest adhesion energy) is that W atoms bonded to C-terminated 4H-SiC with ST(Side Top) stacking sequence, which gives rise to significantly decreasing the total energy. The hybridization of interfacial W1-d and C1-p states is suggestive of formation of covalent bonding. Then the pristine 4H-SiC/W interface is modified by thermal layers, TiN, c- and w-AlN and ZrB2, respectively. The microstructure and electronic property of each energetically favorable interface (i.e., having the largest adhesion energy in consideration of various stacking sequences and terminations) is further scrutinized via several analytic methods. Based on the analysis of microstructure and electronic property of all thermal layers buffered interfaces, the TiN/W, 4H-SiC/TiN, c-AlN/W, ZrB2/W, and 4H-SiC/ZrB2 interfaces are improved via strengthened ionic bonds. Meanwhile, the formation of strong covalent bonds is responsible for enhancement in 4H-SiC/c-AlN and 4H-SiC/w-AlN interface. So, the TiN, c-AlN, and ZrB2 is recommended for further improving the thermal performance of pristine 4H-SiC/W system, wherein embedment of TiN and ZrB2 would increase thickness of conductive layer due to their inherent metallicity. These findings are relevant for technological improvement of pristine 4H-SiC/W interface and present an important scheme for modifying the thermal performance of ceramic/metal components.