Several parameters affect the quality of nano-crystalline Si formed after annealing Of Si/SiO2 multiple quantum wells (MQW). The main parameters influencing the quality are the substrate material, the structure Of Si/SiO2, i.e. number of periods, thickness and composition of the layers and applied annealing procedures. This influence was investigated on MQWs fabricated by RPECVD of alternating Si-rich (amorphous Si and SiOx) and SiO2 layers on quartz and/or on sapphire substrates followed by annealing in rapid thermal annealing (RTA) mode and/or in a furnace. Number and thickness of layers were also varied for various samples. Properties of MQWs were investigated using Raman scattering and photoluminescence (PL) spectroscopy. Large stresses preventing full crystallization of nc-Si layers in MQW were reported previously. A value and a sign of the stress in the MQW layers were monitored by the characteristics of the nc-Si related Raman peak, i.e. spectral position and full-width-on-half-maximurn of the peak. Our results show that the parameters of the stress could be largely tailored by changing substrate and/or structure of MQW. Obtained results show large possibilities for improvement of crystallinity of Si layers by choosing appropriate combination of MQW parameters (thicknesses and number Of Si/SiO2 layers in MQW) and substrate material. (c) 2007 Elsevier B.V. All rights reserved.