Search results for " Silicon"
showing 10 items of 247 documents
Electroluminescence and transport properties in amorphous silicon nanostructures
2006
We report the results of a detailed study on the structural, electrical and optical properties of light emitting devices based on amorphous Si nanostructures. Amorphous nanostructures may constitute an interesting system for the monolithic integration of optical and electrical functions in Si ULSI technology. In fact, they exhibit an intense room temperature electroluminescence (EL), with the advantage of being formed at a temperature of 900 °C, while at least 1100 °C is needed for the formation of Si nanocrystals. Optical and electrical properties of amorphous Si nanocluster devices have been studied in the temperature range between 30 and 300 K. The EL is seen to have a bell-shaped trend …
Short-range order and luminescence in amorphous silicon oxynitride
2000
Abstract Using Si 2p core-level X-ray photoelectron spectroscopy, we found that the short-range order in amorphous silicon oxynitride (a-SiOxNy) can be quantitatively described by a random bonding model. Results also show that the second and even further neighbours of the Si in the network affect the chemical shifts of the X-ray photoelectron spectra. Cathodoluminescence and photoluminescence of a-SiOxNy with different compositions are also measured. A red band with energies of 1.8–1.9 eV, a blue band with an energy of 2.7 eV and ultraviolet bands with energies of 13.1, 3.4–3.6, 4.4–4.7 and 5.4eV were observed. The 1.8–1.9 eV band is attributed to the O and N atoms with an unpaired electron…
Cooling of Hot Electrons in Amorphous Silicon
1997
ABSTRACTMeasurements of the cooling rate of hot carriers in amorphous silicon are made with a two-pump, one-probe technique. The experiment is simulated with a rate-equation model describing the energy transfer between a population of hot carriers and the lattice. An energy transfer rate proportional to the temperature difference is found to be consistent with the experimental data while an energy transfer independent of the temperature difference is not. This contrasts with the situation in crystalline silicon. The measured cooling rates are sufficient to explain the difficulty in observing avalanche effects in amorphous silicon.
Tailoring the Structural, Optical, and Photoluminescence Properties of Porous Silicon/TiO2 Nanostructures
2015
The structural, optical, and photoluminescence properties of porous silicon (PSi)/titanium dioxide (TiO2) nanostructures were investigated. PSi structures consisting of macro- and mesoporous layers were fabricated by metal-assisted chemical etching, and then TiO2 was introduced inside the PSi matrix using the atomic layer deposition technique. We performed scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, energy dispersive X-ray spectroscopy, Raman spectroscopy, ellipsometry, and photoluminescence (PL) spectroscopy to characterize the prepared and annealed PSi/TiO2 nanostructures. TEM and Raman analyses revealed that TiO2 had a crystalline anatase stru…
Extraordinary tuning of a nanocavity by a near-field probe
2011
Abstract We report here an experimental observation of an extraordinary near-field interaction between a local probe and a small-volume solid-state nanocavity. We directly compare the normally observed near-field interaction regime driven by the perturbation theory and then report the extraordinary interaction regime. Subsequently, we show that the cavity can take up to 2 min to recover from this interaction after removing the probe and that leads to an extraordinary blue-shift of the cavity resonance wavelength (∼15 nm) which depends on the probe motion above the cavity and not the position. The reasons for this effect are not fully understood yet but we try to give some explanations.
Facile synthesis and characterization of functionalized, monocrystalline rutile TiO2 nanorods.
2006
Functionalized, monocrystalline rutile TiO2 nanorods were prepared from TiCl4 in aqueous solution under acidic conditions in the presence of dopamine, followed by aging and hydrothermal treatment at 150 degrees C. The surface-bound organic ligand controls the morphology as well as the crystallinity and the phase selection of TiO2. The presence of monocrystalline rutile TiO2 was confirmed by X-ray powder diffraction and HRTEM investigations. The as-prepared nanorods are soluble in water at pH3. The surface functionalization was analyzed by IR and 1H NMR, confirming the presence of dopamine on the surface. The surface amine groups can be tailored further with functional molecules such as dyes…
Superficial defects induced by argon and oxygen bombardments on (110) TiO2 surfaces
1998
Abstract Compositional and chemical changes of titanium dioxide monocrystalline surfaces induced by bombardment with 4 keV argon and oxygen ions have been studied by AES, XPS and AFM. Argon ion bombardment induced strong changes in the composition and chemical state of the surface: loss of oxygen due to preferential sputtering occurred, and, related to this, Ti4+ species were reduced to Ti3+ and Ti2+. During oxygen bombardment, competition between preferential sputtering of oxygen ions of the oxide surface and oxygen implantation was observed. This phenomenon was found to be strongly dependent upon the incidence angle of the oxygen ions. Moreover, an oxygen bombardment with normal incidence…
Polylactic is a Sustainable, Low Absorption, Low Autofluorescence Alternative to Other Plastics for Microfluidic and Organ-on-Chip Applications
2020
Organ-on-chip (OOC) devices are miniaturized devices replacing animal models in drug discovery and toxicology studies. The majority of OOC devices are made from polydimethylsiloxane (PDMS), an elastomer widely used in microfluidic prototyping, but posing a number of challenges to experimentalists, including leaching of uncured oligomers and uncontrolled absorption of small compounds. Here we assess the suitability of polylactic acid (PLA) as a replacement material to PDMS for microfluidic cell culture and OOC applications. We changed the wettability of PLA substrates and demonstrated the functionalization method to be stable over a time period of at least 9 months. We successfully cultured …
Assessment for the mean value total dressing method: Comparison with coupled cluster including triples methods for BF, NO+, CN+, C2, BeO, NH3, CH2, H…
1997
Limited previous experience with the mean value total dressing (MVTD) method had shown that MVTD energies for closed shell systems are generally better than CCSD(T) ones compared to FCI. The method, previously published as total dressing 2′(td-2′), is based on the single reference intermediate Hamiltonian theory. It is not a CC method but deals in a great part with the same physical effects that CC methods that incorporate amplitudes of triples such as CCSDT or its CCSDT-1n approaches. A number of test calculations comparing to diverse CC methods, as well as FCI and experiment when available, have been performed. The tests concern equilibrium energies in NH3 and CH2, equilibrium energies an…