Electroluminescence in silicon oxynitride

The mechanism of electroluminescence (EL) in silicon oxynitride (SiO_xN_y) was investigated. The samples tested were SiO_xN_y films grown by plasma enhanced chemical vapor deposition. The EL can be observed only in the sample with a high nitrogen content and thermally annealed at a high temperature. The EL peak energy decreases from 2.1 eV to 1.7 eV as the nitrogen content increases. It is already known from photoluminescence study that the present samples have at least partially a mixture structure of Si₃N₄ and SiO₂ which are respectively responsible for the two photoluminescence bands at 2.6-2.9 and 2.7 eV in the samples. The conduction in the electric field region where the EL is observable is considered to be governed by the Poole-Frenkel process. From these results, it is concluded that the EL is caused by radiative recombination of electrons and holes in the Si₃N₄ region.