Search results for "CONDUCTIVITY"
showing 10 items of 1988 documents
Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides
2020
The present work elaborates on the correlation between the amount and ordering of the free carbon phase in silicon oxycarbides and their charge carrier transport behavior. Thus, silicon oxycarbides possessing free carbon contents from 0 to ca. 58 vol.% (SiOC/C) were synthesized and exposed to temperatures from 1100 to 1800 °
Crystal shape 2D modeling for transient CZ silicon crystal growth
2013
Abstract A non-stationary axisymmetric model of Czochralski silicon single crystal growth is presented. The model describes transient behavior of crystal–melt, melt–gas and crystal–gas interfaces in connection with PID-based control of crystal diameter by changing crystal pulling velocity and heater power. To calculate significant crystal shape changes, unstructured finite element mesh is used in crystal and melt together with automatic element size control. Heater temperature changes are modeled with a simplified integral model. A numerical simulation example of start cone growth is given.
3D modeling of doping from the atmosphere in floating zone silicon crystal growth
2017
Abstract Three-dimensional numerical simulations of the inert gas flow, melt flow and dopant transport in both phases are carried out for silicon single crystal growth using the floating zone method. The mathematical model allows to predict the cooling heat flux density at silicon surfaces and realistically describes the dopant transport in case of doping from the atmosphere. A very good agreement with experiment is obtained for the radial resistivity variation profiles by taking into account the temperature dependence of chemical reaction processes at the free surface.
Ab initio studies on the lattice thermal conductivity of silicon clathrate frameworks II and VIII
2016
The lattice thermal conductivities of silicon clathrate frameworks II and VIII are investigated by using ab initio lattice dynamics and iterative solution of the linearized Boltzmann transport equation(BTE) for phonons. Within the temperature range 100-350 K, the clathrate structures II and VIII were found to have lower lattice thermal conductivity values than silicon diamond structure (d-Si) by factors of 1/2 and 1/5, respectively. The main reason for the lower lattice thermal conductivity of the clathrate structure II in comparison to d-Si was found to be the harmonic phonon spectra, while in the case of the clathrate structure VIII, the difference is mainly due to the harmonic phonon spe…
Phonon-plasmon coupling in Si doped GaN nanowires
2016
Abstract The vibrational properties of silicon doped GaN nanowires with diameters comprised between 40 and 100 nm are studied by Raman spectroscopy through excitation with two different wavelengths: 532 and 405 nm. Excitation at 532 nm does not allow the observation of the coupled phonon–plasmon upper mode for the intentionally doped samples. Yet, excitation at 405 nm results in the appearance of a narrow peak at frequencies close to that of the uncoupled A 1 (LO) mode for all samples. This behavior points to phonon–plasmon scattering mediated by large phonon wave-vector in these thin and highly doped nanowires.
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
Fabrication of superconducting tantalum nitride thin films using infra-red pulsed laser deposition
2013
We report the successful fabrication of superconducting tantalum nitride (TaN) thin films using a pulsed laser deposition technique with 1064 nm radiation. Films with thickness $ \sim $ 100 nm deposited on MgO (100) single crystals and on oxidized silicon (SiO$_{2} $) substrates exhibited a superconducting transition temperature of $\sim $ 8 K and 6 K, respectively. The topography of these films were investigated using atomic force and scanning electron microscopy, revealing fairly large area particulate free and smooth surfaces, while the structure of the films were investigated using standard $ \theta -2 \theta $ and glancing angle X-ray diffraction techniques. For films grown on MgO a fa…
Correlation Between the Electrical Properties and the Morphology of Low-Pressure MOCVD Titanium Oxynitride Thin Films Grown at Various Temperatures
2000
Titanium oxynitride (TiN x O y ) thin films were deposited by low-pressure metal-organic CVD (LP-MOCVD) on (100) silicon, sapphire, and polycrystalline alumina substrates. Titanium isopropoxide (TIP) and ammonia were used as precursors. The influence of the growth temperature, ranking from 450°C to 750°C, was investigated by scanning electron microscopy (SEM), and electrical DC measurements. Rutherford back-scattering (RBS) measurements were used to determine the N/O ratio in the films. The surface observations of the deposited films showed two morphological transitions. The resistivity decreased with the growth temperature, while the nitrogen content increased. Moreover, for the highest de…
High-Density Arrays of Germanium Nanowire Photoresistors
2006
Here we present for the first time a study of the photoresistive properties and dynamics of ordered, high-density arrays of germanium nanowire photoresistors. Germanium is a wellknown semiconducting material with an indirect bandgap, Eg, of approximately 0.66 eV (temperature T = 300 K) and has been widely used for the fabrication of photodetectors, radiation detectors, charged particle and photon tracking devices, far-infrared photoresistors, and numerous other devices. During the last few years there has also been increasing interest in the use of nanostructures (quantum dots and wires) of both germanium and silicon as materials for potential applications in sensors, nanophotonics, and nan…
Photoconductivity and optical properties of silicon coated by thin TiO2 film in situ doped by Au nanoparticles
2013
Light trapping enhancement by plasmonic-active metal nanoparticles (NPs) is believed to be a promising approach to increase silicon-based solar cell efficiency. Therefore, we investigated TiO2 films in situ doped by Au NPs (TiO2:AuNPs) deposited by spin coating on a silicon substrate. Photoconductivity and optical properties of the TiO2:AuNPs/Si structures were studied in comparison with those of TiO2/Si reference samples. We found that an introduction of the 40–50 nm diameter AuNPs into the antireflective TiO2 layer deteriorates the antireflection properties and decreases the external yield of photogeneration of charge carriers. This is due to an increase of the layer reflection in the red…