Optical Absorbtion And Photoluminescence Properties Of Silicon Nutride Films

As a kind of mufti-functional materials,Silicon nitride thin film is widely used in many fields.In the manufacture of microelectronic materials and devices,silicon nitride thin film is used as passivating film,insulation layer and diffusion mask.In the fabrication of solar cell,silicon nitride thin film is used as passivating film and anti-reflecting film.In the production of luminescent material based on silicon,silicon nitride is used as embed matrix of silicon nanometer clusters.In the paper,the properties,applications and preparation methods of silicon nitride films were overviewed.RF magnetron reaction sputtering Deposition was used to prepare silicon nitride thin films in our experiments.Ar and N₂ as gas source,silicon nitride thin films were grown under several conditions of different substrates and different ratio of Ar and N₂.X-ray Diffraction Spectrum(XRD)was used to analyze the nature and the structure of films.And optical properties of films were discussed using Infrared absorption spectroscop,The photoiuminescence(PL)spectra,PIE spectra and Ultraviolet-Visible spectroscopy(UV-VIS).The result as following:(1)The marked influence of different gas flow ratios to the silicon nitride films is studied. Optical band gap of the silicon nitride films decreases with the increases of ratio of Ar and N₂,and the permeation of the films in visible range is very high.(2)Intrinsic absorption region is showed in Ultraviolet-Visible spectroscopy.Hypo-absorption band being similar to amorphous silicon is found,and it is attributed to dangling bonds on the surface of Silicon particle.(3)Optical characteristics of films within visible scope are very well.The main PL peaks of SiNx films located at 520nm(2.38eV),553nm(2.24 eV),573nm(2.16eV), 587nm(2.11eV),627nm(1.98eV),the excitation wavelength is 381nm.A simple model of gap state was built to explain the PL mechanism of silicon nitride thin films in the paper.