Search results for "SILICON"
showing 10 items of 1391 documents
Electron beam induced optical and electronical properties of SiO 2
2000
Abstract Ionizing radiation in dielectric and optically transparent silica as well as thin SiO 2 layers produces defect luminescence as well as charge storage. A comparison of different excitation–relaxation processes like cathodoluminescence, charge injection and trapping, secondary electron field emission, and exoelectron emission leads to a generally similar excitation dose behaviour described by an electron beam saturation dose of 0.01–0.1 C/cm 2 . This suggests a correlation of these four electron excitation mechanisms likely related to the same kind of defect in glassy SiO 2 , the 2-fold-coordinated silicon Si: centre with typical electronic singlet–singlet and singlet–triplet transit…
Development of a micro-analytical prototype for selective trace detection of orthonitrotoluene
2014
Abstract A silicon micro-analytical platform consisting of a micro-preconcentrator based on a hydrophobic zeolite, coupled to a silicon spiral micro-column was built. A chemical gas sensor acted as a miniaturized gas detector. This system allowed selective detection of orthonitrotoluene (ONT), an explosive-related compound at the sub-ppm level (365 ppb) in the presence of toluene and moisture.
Residual crystalline silicon phase in silicon-rich-oxide films subjected to high temperature annealing
2002
Structural properties of silicon rich oxide films (SRO) have been investigated by means of micro-Raman spectroscopy and transmission electron microscopy (TEM). The layers were deposited by plasma enhanced chemical vapor deposition using different SiH4/O2 gas mixtures. The Raman spectra of the as-deposited SRO films are dominated by a broad band in the region 400-500 cm-1 typical of a highly disordered silicon network. After annealing at temperatures above 1000°C in N2, the formation of silicon nanocrystals is observed both in the Raman spectra and in the TEM images. However, most of the precipitated silicon does not crystallize and assumes an amorphous microstructure. © 2002 The Electrochem…
Novel Method of Preparation of Gold-Nanoparticle-Doped TiO2 and SiO2 Plasmonic Thin Films: Optical Characterization and Comparison with Maxwell-Garne…
2011
SiO2 and TiO2 thin films with gold nanoparticles (NPs) are of particular interest as photovoltaic materials. A novel method for the preparation of spin-coated SiO2–Au and TiO2–Au nanocomposites is presented. This fast and inexpensive method, which includes three separate stages, is based on the in situ synthesis of both the metal-oxide matrix and the Au NPs during a baking process at relatively low temperature. It allows the formation of nanocomposite thin films with a higher concentration of Au NPs than other methods. High-resolution transmission electron microscopy studies revealed a homogeneous distribution of NPs over the film volume along with their narrow size distribution. The optica…
One-step formation of nanostructures on silicon surfaces using pure hydrogen-radical-initiated reactions
2013
One-step formation of silicon nanowires, sheets, and texture surface on a silicon substrate has been achieved using hydrogen-radical etching reactions. Metallic tungsten and for comparison purposes a tungsten hot wire, were used as catalysts for the hydrogen-molecular cracking. It was shown that a variety of surface structures on silicon such as inverted pyramid texture, V-groove texture, dense silicon nanowire growth over texture, and nanosheet structure can be obtained by controlling the process conditions. The obtained results suggested that the formation of nanotungsten silicide particle is an essential prerequisite to obtain these structures. The particles work as an etching mask again…
Improved Temperature Coefficient Modeling through the Recombination Parameter $\gamma$
2020
This study presents an injection dependent numerical model relating Shocldey-Read-Hall defect parameters in crystalline silicon with the recombination parameter $\gamma$ . We demonstrate how the model can be used to predict $\gamma$ for various single level defects. Additionally, we show that $\gamma$ can be significantly influenced by the injection level, in contrast to what is commonly assumed. The injection dependence is found to correlate with the temperature sensitivity of the Shocldey-Read-Hall lifetime. Finally, we demonstrate that the model can be used to predict the temperature coefficient of the open circuit voltage without the use of a temperature dependent measurement, enabling …
Detection and quantification of lung cancer biomarkers by a micro-analytical device using a single metal oxide-based gas sensor
2018
International audience; The analysis of exhaled volatile organic compounds (VOCs) related to lung cancer is a very promising wayin medical diagnosis because it is non-invasive and much less expensive than traditional medical analysisused so far. In that sense, a silicon micro-analytical platform consisting of a micro-preconcentrator cou-pled to a silicon spiral gas chromatographic micro-column was built, and a metal oxide-based gas sensorwas used as a miniaturized gas detector. This micro-fabricated device was successfully tested to selec-tively detect low concentrations of VOCs considered as lung cancer biomarkers, within a few minuteseven in presence of high concentrations of water vapor …
Mechanism of large oscillations of anodic potential during anodization of silicon in H3PO4/HF solutions
2000
Abstract Effect of large oscillations of electrical potential during anodic polarization of silicon in electrolytes composed of phosphoric and hydrofluoric acids has been reported. The oscillations last hours without damping if experimental conditions are optimal. Changes of temperature, anodic current density, intensity of stirring, etc. quench them or convert into less periodic ones. The oscillations are of very high amplitude (typically 15 V) with a period ranging from 18 to 30 s. Scanning electron microscopy (SEM)-imaging of the samples experiencing the oscillatory kinetic behaviour shows unambiguously that the stage of the anodic voltage growth is assisted by the formation of a thin (5…
Character of the Reaction between Molecular Hydrogen and a Silicon Dangling Bond in Amorphous SiO2
2007
The passivation by diffusing H2 of silicon dangling bond defects (E′ centers, O3tSi•) induced by laser irradiation in amorphous SiO2 (silica) is investigated in situ at several temperatures. It is found that the reaction between the E′ center and H2 requires an activation energy of 0.39 eV and that its kinetics is not diffusionlimited. The results are compared with previous findings on the other fundamental paramagnetic point defect in silica, the oxygen dangling bond, which features completely different reaction properties with H2. Furthermore, a comparison is proposed with literature data on the reaction properties of surface E′ centers, of E′ centers embedded in silica films, and with th…
Kinetics of Bulk Lifetime Degradation in Float‐Zone (FZ) Silico n : Fast Activation and Annihilation of Grown‐In Defects and the Role of Hydrogen vs …
2020
Float-zone (FZ) silicon often has grown-in defects that are thermally activated in a broad temperature window (≈300–800 °C). These defects cause efficient electron-hole pair recombination, which deteriorates the bulk minority carrier lifetime and thereby possible photovoltaic conversion efficiencies. Little is known so far about these defects which are possibly Si-vacancy/nitrogen-related (VxNy). Herein, it is shown that the defect activation takes place on sub-second timescales, as does the destruction of the defects at higher temperatures. Complete defect annihilation, however, is not achieved until nitrogen impurities are effused from the wafer, as confirmed by secondary ion mass spectro…