First-principles molecular dynamics study of the thermal stability of the BN, AlN, SiC and SiN interfacial layers in TiN-based heterostructures: Comparison with experiments

Анотація

We conducted first-principles molecular dynamics calculations of the stability and possible transformations of heterostructures consisting of face-centered-cubic (NaCl)-TiN(001) slabs with one monolayer thick pseudomorphically stabilized interfacial layer of B1-type BN, AlN, SiC and SiN, respectively. The calculations have been done with subsequent static relaxation of the heterostructures at temperatures between 0 and 1400 K. It is shown that: i) the BN interfacial layer forms a disordered h-BN-like structure consisting of BN₃ units within the whole temperature range considered; ii) the B1-AlN interfacial layer is stable within the whole temperature range; iii) the B1-SiC interfacial layer transforms into a distorted 3C–SiC(111)-like phase above 600 K; and iv) the SiN interfacial layer consists of SiN₄ and SiN₆ units aligned along the [110] direction at room and high temperatures. Phonon calculations show that the observed modifications of the interfaces are due to the dynamical instability of the B1-type (001) and (111) interfacial layers of BN, SiC and SiN driven by soft modes within the given planes. The results, which can be understood also without the knowledge of the theoretical methods, were used to interpret the available experimental results on TiN-based heterostructures and nanocomposite coatings in order to provide guidance to the experimentalists for the preparation of better coatings.