WHITE ELECTROLUMINESCENCE FROM C- AND SI-RICH THIN SILICON OXIDES

During the last decade, intense investigations have been devoted to the development of an efficient silicon-based optically active material that could enable integration of photonics with Si microelectronics. For example, silicon nanocrystals (Si-ncs) embedded in SiO2 emit in the red and near infrared spectral regions. In this system, light emission has been attributed to quantum confinement or surface states [1–3]. Recently, a few studies have reported broad photoluminescence (PL) in the whole visible domain, by doping Si-rich SiO2 layers with carbon [4, 5]. Blue electroluminescence (EL) emission from such a material has been already reported [6] but efficient EL covering the whole visible spectrum has still to be developed. White light sources compatible with Si technology are interesting for several applications, such as biological and chemical sensors, that need a broad spectral detection, optical interconnectors, or colour display. Some years ago, we have reported white PL of 400 nm thick SiO2 layers by co-implanting Si and C [5]. The PL spectrum is the convolution of emission bands located in the red, green, and blue spectral regions. The structural and optical studies attributed the red band to Si-ncs, observed by TEM. The blue and green bands are linked to C-related nanophase such as SiC- or graphitic-like nanoaggregates, detected by Raman spectroscopy and XPS analysis. Furthermore, the green band shows lifetimes o