Electronic and lattice properties of nanostructured TiN/MgO and ScN/MgO superlattices

Abstract

Various nanostructured TMN(001) dot/MgO(001) (TM = Sc, Ti) superlattices have been investigated. Here, we consider single and double layered TM dot structures with rectangular and rectangular parallelepiped shapes. MgO-2 × 2 and −3 × 3 substrates were used. Their electronic states were obtained using a total energy pseudopotential method. The internal atomic coordinates from the repeated slab model in the unit cell were fully relaxed. Various relaxed structures and electronic properties of the TMN(001) dot/MgO-2 × 2 and −3 × 3 superlattices were obtained. We determined their total and partial densities of states. Peaks of density of states (DOS) of the ScN dot/MgO superlattices around the band gap consist of Sc 3d and N 2p states and those of the TiN dot/MgO superlattices consist of mainly Ti 3d states. The largest band gap value in the TiN(001) dot/MgO(001) (ScN(001) dot/MgO(001)) superlattice is 1.22 eV (1.48 eV) from the density-functional theory-local density approximation calculation. The electronic properties (band gap values, DOS curves, and many more) vary with varying dot shape and substrate size. Most band gap values corrected using a generalized density-functional theory were improved.