Structural study of SiOx amorphous thin films by the grazing incidence x-ray scattering (GIXS) method

Atomic structures of SiOx amorphous thin films of 200 nm thick were analyzed by the grazing incident x-ray scattering (GIXS) method. The radial distribution functions (RDFs) were experimentally determined in two SiOx amorphous thin films grown in the atmosphere with and without N-2 gas. The SiOx amorphous film grown with N-2 gas forms the network structure consisting of SiO4 tetrahedra which are connected each other by oxygen atoms at their vertices. This network structure is similar to the one observed in SiO2 glass. On the other hand, in the SiOx amorphous film grown without N-2 gas, the atomic distance of Si-O pairs is a few percent longer and the coordination number of O-O pairs is smaller than the other. This suggests that some of oxygen atoms in a SiO4 tetrahedron are not connected to a next neighboring tetrahedron. Namely, some part of the network structure is disconnected in the SiOx amorphous film grown without N-2 gas. Due to this imperfection of the network structure, it is expected that the SiOx film grown without N-2 gas would be inferior to the other one grown with N-2 gas in some electrical properties as an insulator.