Influence of the barrier thickness on the photoluminescence properties of amorphous Si/SiO multilayers

Amorphous Si/SiO multilayers have been prepared at 100 °C by successive evaporations of pure silicon and a silicon oxide powder. The silicon thickness is equal to 6 Å and the influence of the barrier thickness is investigated. Photoluminescence in the visible range was observed at room temperature for a barrier thickness greater or equal to 16 Å. Two contributions at 550 and 750 nm are distinguishable. The band at 550 nm is attributed to the silicon oxide layer whereas the photoluminescence at 750 nm is attributed to three dimensionally confined amorphous silicon clusters, which originates from the discontinuity of the amorphous silicon layers.