The structural and optical properties of SiO2/Si rich SiNx multilayers containing Si-ncs

This work reports on the structural and optical properties of multilayers composed of silicon dioxide (SiO2) and silicon rich silicon nitride (SRN) films. These nanometer scale layers have been alternately deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) on quartz and silicon (Si) substrates. The samples have then been annealed at high temperature in order to obtain a crystallization of the Si atoms present in excess in the SRN films. The formation of crystalline Si has been witnessed by high resolution transmission electron microscopy (HREM) and micro-Raman measurements. Estimation of the Si-nanocrystal (Si-nc) sizes was possible by correlating the Raman's confinement model, the photoluminescence measurements and HREM imaging. The results clearly show that the band-gap of the Si-ncs formed can be controlled by this multilayer approach.