Electroluminescence mechanisms in SiO x N y (Si) nanocomposite films

With a view to creating the Si LED, the mechanisms of electroluminescence (EL) in SiOxNy(Si) nanocomposite films with Si nanocrystals embedded in the SiOxNy matrix are studied experimentally and theoretically. The most important results are obtained from a Au/SiOxNySi)/p-Si structure having a semitransparent electrode, the oxynitride film containing Si nanocrystals with a mean size of 3–5 nm and a concentration of ∼1018 cm−3; the measurements are made on a reverse-biased structure (substrate potential negative). Room-temperature EL is observed in the visible and IR ranges; the respective peaks are located at wavelengths of 600–700 and about 1200 nm. The study examines current-voltage characteristics of the structure and the dependence of integrated EL intensity on current, voltage, film thickness, the type of substrate conductivity, etc. The following conclusions are drawn from the experimental and theoretical results: The IR branch is mainly associated with carrier heating, avalanche ionization, and formation of light-emitting microplasmas near the substrate-film interface. The visible branch is linked to (i) hot-electron injection from the substrate into the film and (ii) impact excitation of luminescent centers at nanocrystal-matrix interfaces.