Heterostructures TiN(001)/SiN/TiN(001) and TiN(001)/SiC/TiN(001), with one
monolayer (ML) of interfacial SiN and SiC, respectively, inserted between five monolayer
thick B1-TiN, were investigated using first-principles quantum molecular dynamics
(QMD) calculations. The temperature dependent QMD simulations at 300 K in
combination with subsequent variable-cell structural relaxation revealed that the
TiN(001)/SiN/TiN(001) interface exists as pseudomorphic B1-SiN layer only at 0 K,
and as a superposition of distorted octahedral SiN6 and tetrahedral SiN4 units aligned
along the (110) direction at a finite temperature. Thus, at 300 K, the interfacial layer is
not epitaxial. Instead it consists of aggregates of the B1-SiN-like and Si3N4-like distorted
clusters. However, in the the TiN(001)/SiC/TiN(001) heterostructures, the interfacial
layer remains epitaxial B1-SiC at 0 K as well as at 300 K, with only a small shift of
nitrogen atoms on both sides of the interface towards the silicon atoms. A comparison
with the results obtained by earlier "static" ab initio DFT calculations at 0 K shows the
great advantage of the QMD calculations that allow us to reveal structural reconstructions
caused by thermal activation.
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