Optical absorption analysis is one of the most important technologies for understanding the microstructure of thin films and their band gap properties.For silicon nanostructures

the traditional Tauc method that succeeded in amorphous material is not applicable since the optical absorption of silicon nanostructures would be affected not only by the quantum confinement effect of nanoparticals in the films but also by their concomitant microstructural disorder.In this paper

an optical absorption model for the silicon nitride thin films embedded with amorphous silicon nanoparticles(a-Si NPs/SiNx) is proposed based on quantum confinement effect assuming that a-Si NPs acts a system of three-dimensional confinement quantum dots with a size distribution and the silicon nitride matrix provide a potential barrier.The optical absorption of the films is mainly determined by optical excitation in the system of a-Si NPs.Through simulating the optical absorption spectra of the a-Si NPs/SiNx thin films with above model

we have obtained the size distribution of a-Si NPs and the mean optical gap of the thin films.The effect of surface structural disorder of the a-Si NPs on the optical absorption of the films is also discussed based on the Infrared optical absorption analysis.Agood agreement between the simulated optical absorptions and the experiment results has been obtained in high energy region.Whereas

the deviation of simulated optical absorptions from experiment results in low energy region shows an increased trend.The results show that the quantum confinement effect of a-Si NPs determines the optical absorption of the thin films in high-energy region and the increase of the optical gap is correlated to the decrease of the mean size of the nanoparticles with increasing nitrogen contents.The optical absorption in the low-energy region is mainly generated from the optical excitation in the sub-band states that related to structural disorder and their enhancement in intensity with increasing nitrogen contents can be accounted by the increase of the portion of small a-Si NPs in the films.