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The electrical properties of silicon-rich oxide (SRO) films in metal-oxide-semiconductor-like structures were analysed by current versus voltage (I-V) and capacitance versus voltage (C-V) techniques. SRO films were thermally annealed to activate the agglomeration of the silicon excess in the form of nanoparticles (Si-nps). High current was observed at low negative and positive voltages, and then at a certain voltage (V(drop)), the current dropped to a low conduction state until a high electric field again activated a high conduction state. C-V measurements demonstrated a capacitance reduction at the same time as the current dropped, but without appreciable flat-band voltage (V(FB)) shifting. The reduction in capacitance and current was also observed after applying an electrical stress. These effects are ascribed to the annihilation of conductive paths created by Si-nps. An equivalent circuit is used to explain the capacitance and current reductions. Finally, the conduction mechanism is also analysed by making use of trap assisted tunnelling and Fowler-Nordheim tunnelling at low and high electric fields, respectively.

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In this paper, we study the structural, optical and electro-optical properties of silicon rich oxide (SRO) films, with 6.2 (SRO₃₀) and 7.3 at.% (SRO₂₀) of silicon excess thermally annealed at different temperatures and used as an active layer in light emitting capacitors (LECs). A typical photoluminescence (PL) red-shift is observed as the silicon content and annealing temperature are increased. Nevertheless, when SRO₃₀ films are used in LECs, a resistance switching (RS) behavior from a high current state (HCS) to a low conduction state (LCS) is observed, enhancing the intense blue electroluminescence (EL). This RS produces a long spectral blue-shift (∼227 nm) between the EL and PL band, and it is related to structural defects created by a high current flow through preferential conductive paths breaking off Si-Si bonds from very small silicon nanoparticles (Si-nps) (Eδ (Si ↑ Si ≡ Si) centers). LECs with SRO₂₀ films do not present the RS behavior and only exhibit a slight shift between PL and EL, both in red spectra. The carrier transport in these LEC devices is analyzed as being trap assisted tunnelling and Poole-Frenkel through a quasi 'continuum' of defect traps and quantum dots for the conduction mechanism in SRO₃₀ and SRO₂₀ films, respectively. The results prove the feasibility of obtaining light emitting devices by using simple panel structures with Si-nps embedded in the dielectric layer.

It is well known that silicon-rich oxide (SRO) shows intense photoluminescence (PL). In this work, the authors studied the relationship of the surface morphology and the PL emission. PL spectra of SRO as a function of the excess silicon, temperature, and time of thermal annealing were obtained. The same samples were studied using transmission electronic microscopy and atomic force microscopy to determine their microstructure and surface morphology. A relationship between silicon agglomerates in the SRO and the surface morphology was obtained. Then, the red PL emission was related to the surface morphology. The authors found that the surface roughness is an important parameter for the high red emission of SRO.