Evidence of light-emitting amorphous silicon clusters confined in a silicon oxide matrix

Amorphous silicon oxide thin films were prepared by the coevaporation techn ique in ultrahigh vacuum. Different compositions were obtained by changing the evaporation rate of silicon. The samples were then annealed to differen t temperatures up to 950 degreesC. The composition and the structure were i nvestigated using energy dispersive x-ray spectroscopy, infrared absorption measurements, and Raman spectroscopy. This study attests the presence of a morphous silicon clusters in a silicon oxide matrix. Optical transmission m easurements were performed and interpreted in the field of the composite me dium theory. The obtained results are in good agreement with the presented structural model. The photoluminescence in the red-orange domain was studie d in relation with the structure. The correlation between the photoluminesc ence energy and intensity and the structure shows that the light emission o riginates from the silicon clusters embedded in the silicon oxide matrix. M oreover the dependence of the photoluminescence energy with the silicon vol ume fraction suggests the origin of the light emission could be due to a qu antum confinement effect of carriers in the amorphous silicon clusters. (C) 2001 American Institute of Physics.