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

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.