scholarly journals Theory of electron--phonon scattering effects in metals. Progress report, March 1--November 30, 1973

1973 ◽  
Author(s):  
W.E. Lawrence
Keyword(s):  
Phonon Scattering ◽  
Progress Report ◽  
Scattering Effects ◽  
Electron Phonon Scattering

scholarly journals Modeling of Thermoelectric Properties of Semi-Conductor Thin Films With Quantum and Scattering Effects

2006 ◽  
Vol 129 (4) ◽  
pp. 492-499 ◽  
Author(s):  
A. Bulusu ◽  
D. G. Walker
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Phonon Scattering ◽  
Quantum Effects ◽  
Effect Of Temperature ◽  
Fundamental Parameters ◽  
Scattering Effects ◽  
Electron Phonon Scattering

Several new reduced-scale structures have been proposed to improve thermoelectric properties of materials. In particular, superlattice thin films and wires should decrease the thermal conductivity, due to increased phonon boundary scattering, while increasing the local electron density of states for improved thermopower. The net effect should be increased ZT, the performance metric for thermoelectric structures. Modeling these structures is challenging because quantum effects often have to be combined with noncontinuum effects and because electronic and thermal systems are tightly coupled. The nonequilibrium Green’s function (NEGF) approach, which provides a platform to address both of these difficulties, is used to predict the thermoelectric properties of thin-film structures based on a limited number of fundamental parameters. The model includes quantum effects and electron-phonon scattering. Results indicate a 26–90 % decrease in channel current for the case of near-elastic, phase-breaking, electron-phonon scattering for single phonon energies ranging from 0.2 meV to 60 meV. In addition, the NEGF model is used to assess the effect of temperature on device characteristics of thin-film heterojunctions whose applications include thermoelectric cooling of electronic and optoelectronic systems. Results show the predicted Seebeck coefficient to be similar to measured trends. Although superlattices have been known to show reduced thermal conductivity, results show that the inclusion of scattering effects reduces the electrical conductivity leading to a significant reduction in the power factor (S2σ).

Thermal Modeling of Very Small Scale Devices

2004 ◽  
Author(s):  
A. Bulusu ◽  
D. G. Walker
Keyword(s):  
Phonon Scattering ◽  
Electronic Device ◽  
Electron Tunneling ◽  
Quantum Effects ◽  
Small Scale ◽  
Channel Current ◽  
Scattering Rate ◽  
Scattering Effects ◽  
Computationally Intensive ◽  
Electron Phonon Scattering

As electronic device dimensions shrink down to the nanoscale regime, quantum effects such as electron tunneling and quantum confinement become significant. Along with quantum effects, various scattering processes such as carrier-carrier and carrier-defect scattering will influence device performance. Many transport models are not mature enough to couple the thermal effects with electronic solutions at such small scales. Incorporation of strong scattering influences on the electron transport in most cases is extremely difficult and computationally intensive. In this paper, we study a simple model that allows for integration of electron-phonon scattering effects in a nanotransistor. An acoustic deformation potential based electron-phonon scattering model is used to incorporate scattering in the device. A 7.5% drop in channel current was observed for a scattering rate of 1013/sec while current flow dropped by 50% for higher scattering rates. The effective channel resistance due to scattering was found to increase by a factor of 1.3. The results are compared to the I-V characteristics obtained using the non-equilibrium Green’s function (NEGF) formalism and were found to match well. The effect of phase-breaking scattering was also studied using NEGF where a 25% decrease in channel current was obtained thus demonstrating the importance of including scattering effects with quantum transport.

Modeling of Electron Transport in Thin Films With Quantum and Scattering Effects

2005 ◽  
Author(s):  
A. Bulusu ◽  
D. G. Walker
Keyword(s):  
Electron Transport ◽  
Phonon Scattering ◽  
Simulation Models ◽  
Quantum Effects ◽  
Effect Of Temperature ◽  
Channel Current ◽  
Couple Quantum ◽  
Scattering Effects ◽  
Computationally Intensive ◽  
Electron Phonon Scattering

With device dimensions shrinking to nanoscales, quantum effects such as confinement and tunneling become significant in electron transport. In addition, thermal transport in devices is directly coupled to charge transport even in highly scaled devices. While electron-phonon scattering usually helps restore thermodynamic equilibrium, shrinking device dimensions may not ensure enough scattering to restore equilibrium. The simultaneous consideration of scattering effects, which is usually described as particle behavior, and quantum effects, which are wave in nature, is extremely difficult and computationally intensive. Most device transport simulation models are not mature enough to couple quantum effects with strong scattering effects. In this paper, we couple quantum effects and scattering influences on electron transport using the non-equilibrium Green’s function formalism. Results indicate a 45 to 70 percent decrease in channel current for the case of near-elastic, phase-breaking, electron-phonon scattering. The single phonon energies ranged from 2meV to 20meV. The results illustrate the importance of including scattering effects with quantum transport. In addition, the NEGF model is used to assess the effect of temperature on device characteristics of thin film superlattices whose applications include thermoelectric cooling of electronic and optoelectronic systems. Results show the predicted Seebeck coefficient to be in good agreement with the measured values.

TEMPERATURE DEPENDENCE BEHAVIOR OF ELECTRICAL RESISTIVITY IN NOBLE METALS AT LOW TEMPERATURES

2014 ◽  
Vol 5 (3) ◽  
pp. 982-992 ◽  
Author(s):  
M AL-Jalali
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Low Temperatures ◽  
Noble Metals ◽  
Phonon Scattering ◽  
Theoretical Models ◽  
Residual Resistivity ◽  
Electron Phonon Scattering

Resistivity temperature – dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron – dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

scholarly journals When band convergence is not beneficial for thermoelectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junsoo Park ◽  
Maxwell Dylla ◽  
Yi Xia ◽  
Max Wood ◽  
G. Jeffrey Snyder ◽  
...  
Keyword(s):  
Charge Carrier ◽  
First Principles ◽  
Design Principle ◽  
Phonon Scattering ◽  
Charge Carrier Concentration ◽  
Deformation Potential ◽  
Interband Scattering ◽  
Improved Performance ◽  
Full Heusler ◽  
Electron Phonon Scattering

AbstractBand convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg2Sb2-CaZn2Sb2 Zintl system and full Heusler Sr2SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

scholarly journals 2D weak anti-localization in thin films of the topological semimetal Pd$$_{3}$$Bi$$_{2}$$S$$_{2}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shama ◽  
R. K. Gopal ◽  
Goutam Sheet ◽  
Yogesh Singh
Keyword(s):  
Thin Films ◽  
Phonon Scattering ◽  
Surface States ◽  
Relaxation Mechanism ◽  
Transport Studies ◽  
Bulk Carriers ◽  
Topological Semimetal ◽  
Topological Surface ◽  
First Time ◽  
Electron Phonon Scattering

AbstractPd$$_{3}$$ 3 Bi$$_{2}$$ 2 S$$_{2}$$ 2 (PBS) is a recently proposed topological semimetal candidate. However, evidence for topological surface states have not yet been revealed in transport measurements due to the large mobility of bulk carriers. We report the growth and magneto-transport studies of PBS thin films where the mobility of the bulk carriers is reduced by two orders of magnitude, revealing for the first time, contributions from the 2-dimensional (2D) topological surface states in the observation of the 2D weak anti-localization (WAL) effect in magnetic field and angle dependent conductivity measurements. The magnetotransport data is analysed within the 2D Hikami-Larkin-Nagaoka (HLN) theory. The analysis suggests that multiple conduction channels contribute to the transport. It is also found that the temperature dependence of the dephasing length can’t be explained only by electron-electron scattering and that electron-phonon scattering also contributes to the phase relaxation mechanism in PBS films.

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