Abstract
In this work, the structural and optical properties of co-sputtered SRO (Silicon Rich Oxide) films are studied as a function of the annealing temperature and the change in the Si (Silicon) content. Si-excess of 4.4–16.9at.% were obtained by a variation of RF-power densities applied to Si target from 1.97 to 3.94W/cm2, respectively. The Si-excess calculated by XPS promotes the formation of Si clusters within SRO films where the size depends on the Si-excess quantity. After annealing, ultra-small oxidized silicon nanocrystals (Si-NCs) and agglomeration of Si-excess, promotes the possible creation of Si=O, centers like Eδ′ and ODC defects at the surface of Si-NCs. Therefore, two broad Photoluminescence (PL) bands are observed in the red (1.5–1.7eV) and blue (2–2.9eV) region. A high emission intensity in red region is observed in sample with 5.9at.% of Si-excess, which could be related with a complete activation of defects (Si=O) favored by the dominant average size of the Si-NCs (1.68nm). The density and average size of Si-NCs increase according to Si-excess, whereby a decrease in PL intensity is observed. Thus, a considerable Si-excess (>10at.%) is not necessary to obtain the maximum PL emission in red region.
Published Version
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