Hole mobility in Cu2O.I. Scattering by lattice vibrations

1970 ◽  
Vol 48 (22) ◽  
pp. 2643-2656 ◽  
Author(s):  
R. Kužel ◽  
F. L. Weichman
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Vibrational Spectrum ◽  
Temperature Dependence ◽  
Optical Phonon ◽  
Hall Current ◽  
Hole Mobility ◽  
Guard Ring ◽  
Lattice Vibrations ◽  
Optical Phonons

The hole mobility in Cu2O was measured using guard ring and Hall current techniques over a temperature range of +200 to −125 °C. For samples with highest mobility the temperature dependence was found to be approximately exponential with different activation energy above and below +60 °C. The results are explained on the basis of the known vibrational spectrum of Cu2O with polar scattering by an optical phonon of 0.0795 eV and nonpolar scattering by optical phonons of 0.139, 0.023, and 0.0185 eV predominating. Variations in mobility due to changes in dielectric constant are also discussed.

Electron-Phonon Interaction and Joule Heating in Nanostructures

2008 ◽  
Author(s):  
Eric Pop
Keyword(s):  
Carbon Nanotubes ◽  
Electric Fields ◽  
Joule Heating ◽  
Optical Phonon ◽  
Phonon Transport ◽  
Phonon Energy ◽  
Strained Silicon ◽  
Vibrational Modes ◽  
Optical Phonons ◽  
Ambient Gas

The electron-phonon energy dissipation bottleneck is examined in silicon and carbon nanoscale devices. Monte Carlo simulations of Joule heating are used to investigate the spectrum of phonon emission in bulk and strained silicon. The generated phonon distributions are highly non-uniform in energy and momentum, although they can be approximately grouped into one third acoustic (AC) and two thirds optical phonons (OP) at high electric fields. The phonon dissipation is markedly different in strained silicon at low electric fields, where certain relaxation mechanisms are blocked by scattering selection rules. In very short (∼10 nm) silicon devices, electron and phonon transport is quasi-ballistic, and the heat generation domain is much displaced from the active device region, into the contact electrodes. The electron-phonon bottleneck is more severe in carbon nanotubes, where the optical phonon energy is three times higher than in silicon, and the electron-OP interaction is entirely dominant at high fields. Thus, persistent hot optical phonons are easily generated under Joule heating in single-walled carbon nanotubes suspended between two electrodes, in vacuum. This leads to negative differential conductance at high bias, light emission, and eventual breakdown. Conversely, optical and electrical measurements on such nanotubes can be used to gauge their thermal properties. The hot optical phonon effects appear less pronounced in suspended nanotubes immersed in an ambient gas, suggesting that phonons find relaxation pathways with the vibrational modes of the ambient gas molecules. Finally, hot optical phonons are least pronounced for carbon nanotube devices lying on dielectrics, where the OP modes can couple into the vibrational modes of the substrate. Such measurements and modeling suggest very interesting, non-equilibrium coupling between electrons and phonons in solid-state devices at nanometer length and picoseconds time scales.

Temperature dependence of low-frequency optical phonons in TlInS2

2015 ◽  
Vol 12 (6) ◽  
pp. 826-829 ◽  
Author(s):  
Raul Paucar ◽  
YongGu Shim ◽  
Kazuki Wakita ◽  
Oktay Alekperov ◽  
Nazim Mamedov
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Optical Phonons

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

scholarly journals Synthesis and electrical characterization of Ca2Nd4Ti6O20 ceramics

2016 ◽  
Vol 34 (1) ◽  
pp. 164-168
Author(s):  
Raz Muhammad ◽  
Muhammad Uzair ◽  
M. Javid Iqbal ◽  
M. Jawad Khan ◽  
Yaseen Iqbal ◽  
...  
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Room Temperature ◽  
Sol Gel ◽  
Electrical Characterization ◽  
Sintered Sample ◽  
First Time ◽  
Alkoxide Precursors ◽  
Room Temperature Dielectric Constant

AbstractCa2Nd4Ti6O20, a layered perov skite structured material was synthesized via a chemical (citrate sol-gel) route for the first time using nitrates and alkoxide precursors. Phase analysis of a sample sintered at 1625 °C revealed the formation of an orthorhombic (Pbn21) symmetry. The microstructure of the sample after sintering comprised rod-shaped grains of a size of 1.5 to 6.5µm. The room temperature dielectric constant of the sintered sample was 38 at 100 kHz. The remnant polarization (Pr) and the coercive field (Ec) were about 400 μC/cm2 and 8.4 kV/cm, respectively. Impedance spectroscopy revealed that the capacitance (13.7 pF) and activation energy (1.39 eV) of the grain boundary was greater than the capacitance (5.7 pF) and activation energy (1.13 eV) of the grain.

Über die Deutung der Gleichstromleitfähigkeit organischer Flüssigkeiten bei niedrigen Temperaturen

1964 ◽  
Vol 19 (9) ◽  
pp. 1070-1075
Author(s):  
H. Vogel ◽  
H. Bässler
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Liquid State ◽  
Static Dielectric Constant ◽  
Coulomb Energy ◽  
Organic Liquids ◽  
Characteristic Distance ◽  
Lower Region ◽  
Pure Coulomb ◽  
The Law

The activation energy of the d. c. conductance of organic liquids lies between 0.04 and 0.45 eV in the lower region of temperature of their liquid state. A comparison of these values with the static dielectric constant shows, that the activation energy may be regarded as a pure COULOMB energy: E2 = e2/2 ε r . The characteristic distance r has the approximate value of 8.5 Å for hydrocarbons. It decreases for halogen- and nitro-derivates. Formerly it was found that the conductivity of mixtures obeys the law σM = σAC · σB1-C. This can easily be explained assuming εM = c εA + (1 — c) εB. In the case of rather different ε values or of homologuous compounds forming complexes, σ increases. This is identical with a kink in the log σ (c) -curve.

Study of anharmonicity in pure and doped InSe by Raman scattering

2018 ◽  
Vol 32 (30) ◽  
pp. 1850340 ◽  
Author(s):  
Mahmoud Zolfaghari
Keyword(s):  
Raman Scattering ◽  
Temperature Dependence ◽  
Temperature Variation ◽  
Optical Phonon ◽  
Line Center ◽  
Anharmonic Effect ◽  
Layered Semiconductor ◽  
Center Shift ◽  
Raman Modes ◽  
Quartic Anharmonicity

With the help of temperature dependence, Raman scattering anharmonic effect of various modes of layered semiconductor InSe over temperature range of 20–650 K has been studied. It was found that with an increase in temperature, anharmonicity will increase. Two and three phonons coupling with optical phonon, are used to describe temperature-induced anharmonicity in the linewidth of Raman modes. It was found that the temperature variation of the phonon parameter can be accounted for well by the cubic term in anharmonic model. To describe line-center shift of Raman modes, a model not considering independently cubic and quartic anharmonicity was used. A similar study has been done for InSe doped with different concentration of GaS dopant. The result of temperature study of InSe doped with GaS revealed that in this case anharmonicity increases with an increase in dopant and an increase in temperature.

P+ implanted 6H-SiC n+-i-p diodes: evidence for a post-implantation-annealing dependent defect activation

2014 ◽  
Vol 1693 ◽  
Author(s):  
R. Nipoti ◽  
M. Puzzanghera ◽  
F. Moscatelli
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Ideality Factor ◽  
Low Voltage ◽  
Reverse Current ◽  
Forward Current ◽  
Current Region ◽  
Recombination Centers ◽  
Energy Dependent ◽  
Post Implantation

ABSTRACTTwo n+-i-p 6H-SiC diode families with P+ ion implanted emitter have been processed with all identical steps except the post implantation annealing: 1300°C/20min without C-cap has been compared with 1950°C/10min with C-cap. The analysis of the temperature dependence of the reverse current at low voltage (-100V) in the temperature range 27-290°C shows the dominance of a periphery current which is due to generation centers with number and activation energy dependent on the post implantation annealing process. The analysis of the temperature dependence of the forward current shows two ideality factor n region, one with n = 1.9/2 at low voltage and the other one with 1 < n < 2 without passing through 1 for increasing voltages. For both the diode families the current with n = 1.9/2 is a periphery current due to recombination centers with a thermal activation energy near the 6H-SiC mid gap. In the forward current region of 1 < n < 2, the two diode families show different ideality factor values which could be attributed to a different post implantation annealing defect activation.

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