First-Principles Study of TiN/MgO Interfaces

Abstract

TiN(001)/MgO(001) interfaces have been investigated by using the total energy pseudopotential method. Their relaxed interface structures and electronic properties (charge densities, electronic band structures, density of states, etc.) were obtained. All the calculated electronic states of the TiN/MgO interfaces correspond to metallicity. Upon full structural relaxation of these interfaces, the cation (Ti) and anion (N) atoms on the interface layer are rumpled. This trend of atomic displacements at the interface layer is similar to that observed in the rumpled surface layer of transition metal carbides (TMCs) and nitrides (TMNs). We calculated the energies of two bonding configurations at the TiN/MgO interface. One is a cation-anion (Ti-O and Mg-N) bonding configuration across the interface. The other is a cation-cation (Ti-Mg) and anion-anion (N-O) bonding configuration across the interface. The former is energetically more stable than the latter by 2.31 eV. We investigated the TiN/MgO interface with a oxygen vacancy (O vacancy) for both of the abovementioned two bonding configurations. The formation energies of the O vacancy for the TiN/MgO(IV) and TiN/MgO(X) bonding cases are 6.90 eV and 6.79 eV, respectively. These values are positive and large. This indicates that the TiN/MgO interface with the O vacancy is energetically unfavorable.

Atomic and electronic structure of the TiN/MgO interface from first principles

“…It was found that the interface with cation-anion bonding configurations (namely, Ti-O and Mg-N) is energetically favorable for TiN(0 0 1)/ MgO(0 0 1) interfaces which agree well with other reported theoretical results [16,17] and the interface with N(Ti) atoms located above bridge sites between Mg(O) atoms of TiN(1 1 0)/ MgO(1 1 0) interfaces shows the largest adhesion energy; in addition, the orientation relationship has a significant impact on the stability of the interface, which can account for the substantial effect of the substrate on the growth direction of nanowires [10]. By applying some analytical methods, we characterized the interfacial electronic structure.…”

Electronic Band Structure of Various TiN/MgO Superlattices

“…The lattice mismatch of TiN and MgO is 1.4%. [20] are also tabulated. Their electronic states ("Metal", "Semimetal", and "Semiconductor") are tabulated.…”

“…A partial core correction (PCC) [31] is considered for the Sc, Ti, V, Nb, and Mg pseudopotentials. Two types of Mg pseudopotentials were prepared in the previous study [20]. In this study we chose the Mg pseudopotential which is more suitable for the TiN/MgO superlattice with a smaller lattice mismatch of TiN and MgO.…”

“…"n + m" is the total layer number of the TiN/MgO superlattice in the supercell. (TiN) 4 /(MgO) 4 and (TiN) 8 /(MgO) 8 have already been investigated previously [20].…”

“…We have investigated TiN(001)/MgO(001) interfaces previously [20] in order to support experimental results [21] (detailed structural and electronic properties) of the TiN thin film on a MgO substrate using molecular beam epitaxy. The electronic structures of all the TiN(001)/MgO(001) superlattices calculated in the previous study [20] correspond to metallicity.…”