Properties of silicon nanoparticles embedded in SiNx deposited by microwave-PECVD.

In this work, silicon-rich silicon nitride (SRN) layers were deposited on a silicon wafer by microwave-assisted plasma-enhanced chemical vapor deposition (MW-PECVD) using NH(3) and SiH(4) as precursor gases. The Si excess in the as-deposited layers as determined by the Rutherford backscattering technique was controlled by varying the precursor gas ratio. We were able to produce silicon nanoparticles (Si-nps) in the silicon nitride (SiN(x)) layers upon thermal annealing at high temperature. Energy-filtered TEM (EFTEM), complemented by photoluminescence measurements, were used to identify the experimental parameters in order to reach a high density of well-separated Si-nps (3 nm). Our results show that the MW-PECVD method is a suitable deposition tool for the formation of Si-nps in thin SRN layers.

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.