Search results for " Conduction"
showing 10 items of 373 documents
Mechanisms of Strong Photoluminescence from Si Nanocrystals
2011
Photoluminescence mechanisms (models) are reviewed and experimental data are analyzed based on our model, related to direct radiative transitions from the second conduction sub-band to the first one.
<title>New aspect of light emission from silicon nanocrystals</title>
2003
Intensive light emission (photoluminescence) from silicon nanocrystals has been interpreted in literature as recombinative emission. It has been supposed that the band structure is "pseidodirect." The literature analysis presented in our paper shows that the band structure is indirect and therefore intensive recombinative emission is not possible. According to new aspect, a part of electrons reaches the second conduction subband due to Auger recombination. Then the intensive visible radiation could be caused by transitions of these electrons from the second to the first conduction subband. We have constructed continuity equations for the electron concentration in the first and the second co…
Thickness-dependent electron momentum relaxation times in iron films
2020
Terahertz time-domain conductivity measurements in 2 to 100 nm thick iron films resolve the femtosecond time delay between applied electric fields and resulting currents. This current response time decreases from 29 fs for thickest films to 7 fs for the thinnest films. The macroscopic response time is not strictly proportional to the conductivity. This excludes the existence of a single relaxation time universal for all conduction electrons. We must assume a distribution of microscopic momentum relaxation times. The macroscopic response time depends on average and variation of this distribution; the observed deviation between response time and conductivity scaling corresponds to the scaling…
Structural and Electric Properties of Sodium Lithium Niobate Ceramic Solid Solution Li0.08Na0.92NbO3
2011
A lead-free solid solution Li0.08Na0.92NbO3 was prepared by a two-stage hot-pressing technology. The structure and morphology of Li0.08Na0.92NbO3 were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The studies of electric conductivity were performed depending on temperature and frequency of electric measuring field on heating and cooling processes. These measurements revealed that the a.c. conductivity changed with the frequency according to the formula: σ(ω)=σ dc +Aω n where n < 1. These results were discussed considering the conduction mechanism as a type of polaron hopping.
Electron-phonon heat transport and electronic thermal conductivity in heavily doped silicon-on-insulator film
2003
Electron–phonon interaction and electronic thermal conductivity have been investigated in heavily doped silicon at subKelvin temperatures. The heat flow between electron and phonon systems is found to be proportional to T6. Utilization of a superconductor–semiconductor–superconductor thermometer enables a precise measurement of electron and substrate temperatures. The electronic thermal conductivity is consistent with the Wiedemann–Franz law. Peer reviewed
Vertical osteoconductivity and early bone formation of titanium-zirconium and titanium implants in a subperiosteal rabbit animal model.
2013
Objectives The aim of this pilot study was to evaluate the vertical osteoconductive and osteointegrative dynamics around titanium–zirconium (TiZr) implants compared to titanium (Ti) implants. Materials and methods In a split-leg design, 12 TiZr-SLActive and 12 Ti-SLActive implants were inserted 3 mm above bone level in the proximal tibia of 12 rabbits. Full periosteal flaps were repositioned to cover the site. Specimens were obtained after 10, 20 and 30 days (each n = 4 per group). Histomorphometric measurements included percentage of linear bone fill (PLF; %), new marginal vertical bone height (VBH; mm) and vertical bone-to-implant contact (vBIC; %). Statistical analysis was performed with…
Heat transport of helium II in restricted geometries
1979
The linear heat transport of helium II contained in porous powder samples with mean pore diameters of 1.25µm, 0.17µm and 0.02µm was systematically studied in the temperature range between 0.8 K and 2 K. The effective thermal conductivity was determined by steady-state heat flow measurements and the effective thermal diffusivity by transitory temperature measurements. The experimental results are interpreted by a simple theoretical model. In the framework of this model the linear heat transport consists of two contributions: the laminar flow of the normal fluid (T≳1.4 K) and a diffusion mechanism (T≲1.4 K). At low temperatures (T≲1.2 K) the mean free paths of the elementary excitations of he…
Surfactant effect of Sb on the growth of Ag films on a sapphire substrate
1996
It is shown that a very thin layer of Sb may be used as a surfactant to modify the growth of silver films on an insulating substrate. The conduction (percolation) current flowing through a dispersed Ag film appears at a significantly smaller thickness due to the change in the growth mode of silver islands. Some practical applications are indicated.
Controlling the mode of operation of organic transistors through side chain engineering
2016
Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode…
Prediction of the growth interface shape in industrial 300mm CZ Si crystal growth
2004
Abstract A model approach for a modification of the effective heat conductivity in the turbulent melt flow simulation for 28″ Si CZ crucibles is presented, which helped to overcome deficiencies in the growth interface shape prediction for industrial 300 mm Si CZ growth. The model has been incorporated into a CZ simulation tool based on the simulation software codes FEMAG for the global heat transfer and CFD-ACE for the turbulent melt flow simulation. The model predictions are compared to results from 300 mm Si CZ growth experiments with 200 kg charge weight in 28″ crucibles in a growth parameter range covered by standard industrial processes. The model is an engineering approach. Neverthele…