Atomic and electronic structures of a-ZnSnO₃/a-SiO₂interface byab initiomolecular dynamics simulations

Abstract

The interface between amorphous ZnSnO3 and amorphous SiO2 was investigated by ab initio molecular dynamic simulations. The radial distribution function at the interfacial region shows the significant reduction of the coordination numbers of Zn and Sn and slight decrease in the bond lengths of Zn–O and Sn–O, while keeping those of Si. These phenomena were explained in terms of the differences in both the coordination states of oxygen polyhedra and the connectivity of oxygen polyhedra between amorphous ZnSnO3 and amorphous SiO2. The interfacial energy was calculated to be 0.73 J cm−2 by the annealing at 300 K, while it was 0.29 J cm−2 by the annealing at 900 K, respectively. The reduction of the interfacial energy at higher annealing temperature was considered to be attributed to the increase of the number of M–O–Si bonds (M=Zn and Sn). The interfacial states in the density of states observed at the interface region was induced by the 2p states of oxygen having the decreased coordination number, and the interfacial gap states were not removed even by the 900 K annealing.

Orientation-dependent structural and electronic properties of Ge/a-GeO2 interfaces: first-principles study

“…It is the lowest for Ge(1 0 0)/a-GeO 2 [7.9 (±2.0) cm −2 ] and the highest for Ge(1 1 1)/a-GeO 2 [11.8 (±2.1) cm −2 ], showing a tendency opposite to that of the interface energy. It should be pointed out that an increased density of bonds formed across the interface contributes to interface stability, resulting in a decrease in the interface energy, as suggested by the behavior at the interface between two amorphous materials [22]. The behaviors of the interface energy and bond density may be attributed to the properties of the Ge bare surfaces: the Ge(1 1 1) and Ge(1 1 0) surfaces form one DB per surface Ge atom, while Ge(1 0 0) forms two DBs per surface Ge atom, leaving a larger DB density at the (1 0 0) surface.…”