Influence of annealing treatments on the photoluminescence properties of a-SiNx: H films

Hydrogenated amorphous silicon nitride (a-SiN_x: H) films were prepared by plasma enhanced chemical vapor deposition (PECVD) with silane and ammonia. After different temperature annealing treatments the bonding configuration and photoluminescence (PL) mechanisms of the samples were studied by Fourier-transform infrared spectroscopy and Fluorescence spectrometer. With the increase of annealing temperature (T_A), there formed in the films approximately stoichiometric Si₃N₄ phase, while hydrogen disappeared gradually. The PL spectra of the annealed samples consisted of four peaks at 2.95, 2.62, 2.40 and 2.13 eV respectively, which had no obvious shift with different T_A. And the peak intensities reached the maximum values when the samples were annealed at 800 °C. These four PL peaks were assigned to the great amount of radiative recombination defects such as ≡Si⁰, N⁰₂, N⁺₄, Si-O-Si and N-Si-O.