International audienceWe report a study of resistive switching in a silicon-based memristor/resistive RAM (RRAM)device in which the active layer is silicon-rich silica. The resistive switching phenomenon is anintrinsic property of the silicon-rich oxide layer and does not depend on the diffusion of metallicions to form conductive paths. In contrast to other work in the literature, switching occurs inambient conditions, and is not limited to the surface of the active material. We propose a switchingmechanism driven by competing field-driven formation and current-driven destruction offilamentary conductive pathways. We demonstrate that conduction is dominated by trap assistedtunneling through noncontinuous conduction paths consisting of silicon nanoinclusions in a highlynonstoichiometric suboxide phase. We hypothesize that such nanoinclusions nucleate preferentiallyat internal grain boundaries in nanostructured films. Switching exhibits the pinched hysteresis I/Vloop characteristic of memristive systems, and on/off resistance ratios of 104:1 or higher can beeasily achieved. Scanning tunneling microscopy suggests that switchable conductive pathways are10 nm in diameter or smaller. Programming currents can be as low as 2 lA, and transition timesare on the nanosecond scale

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This study reports the estimation of the inverted Er fraction in a system of Er doped silicon oxide sensitized by Si nanoclusters, made by magnetron sputtering. Electroluminescence was obtained from the sensitized erbium, with a power efficiency of 10 −2 %. By estimating the density of Er ions that are in the first excited state, we find that up to 20% of the total Er concentration is inverted in the best device, which is one order of magnitude higher than that achieved by optical pumping of similar materials. ©2009 Optical Society of America

This study attempts to clarify the origin of the temperature dependence of the photoluminescence ͑PL͒ spectra of silicon nanocrystals ͑Si-ncs͒ embedded in SiO 2 from 5 to 300 K. For this purpose, size-controlled Si-ncs with a narrow size distribution were fabricated, using the SiO/ SiO 2 multilayer structure. The PL intensity is strongly temperature dependent and presents a maximum at around 70 K, depending on the Si-nc size and on the excitation power. The origin of this maximum is first discussed thanks to PL dynamics study and power dependence study. The evolution of the PL energy with temperature is also discussed. In bulk semiconductors the temperature dependence of the gap is generally well represented by Varshni's law. Taking into account the quantum confinement energy, the PL energy of Si-ncs follows very well this law in the range 50-300 K. Below 50 K, a strong discrepancy to this law is observed characterized by a strong increase in the PL energy at low temperature, which is dependent on the Si-nc size distribution. This temperature dependence of the PL energy is correlated with a decrease in the radiative rate at low temperature and is explained by a preferential saturation effect of the bigger Si-ncs.