Electron-phonon scattering effects on electronic and optical properties of orthorhombic GeS

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).

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Thermal Modeling of Very Small Scale Devices

Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology ◽

10.1115/imece2004-59858 ◽

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.

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Electron–phonon scattering and excitonic effects in T-carbon

RSC Advances ◽

10.1039/d0ra02343d ◽

2020 ◽

Vol 10 (41) ◽

pp. 24515-24520 ◽

Cited By ~ 1

Author(s):

Xiangtian Bu ◽

Shudong Wang

Keyword(s):

Optical Properties ◽

Perturbation Theory ◽

First Principles ◽

Phonon Scattering ◽

First Principles Calculations ◽

Many Body ◽

Many Body Perturbation Theory ◽

Excitonic Effects ◽

Electron Phonon Scattering

Through first-principles calculations combining many-body perturbation theory, we investigate electron–phonon scattering and optical properties including the excitonic effects of T-carbon.

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Electron-Phonon Scattering Effects on the Pair Breaking Parameter in Al, Sn and Pb Superconducting Films

Journal of the Physical Society of Japan ◽

10.1143/jpsj.59.1039 ◽

1990 ◽

Vol 59 (3) ◽

pp. 1039-1046 ◽

Cited By ~ 8

Author(s):

Bunjyu Shinozaki ◽

Takasi Kawaguti ◽

Yasunobu Fujimori

Keyword(s):

Phonon Scattering ◽

Superconducting Films ◽

Pair Breaking ◽

Scattering Effects ◽

Breaking Parameter ◽

Electron Phonon Scattering

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

Advances in Electronic Packaging, Parts A, B, and C ◽

10.1115/ipack2005-73212 ◽

2005 ◽

Cited By ~ 1

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.

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Theory of Electronic, Optical and Transport Properties in Silicon Quantum Wires

MRS Proceedings ◽

10.1557/proc-283-419 ◽

1992 ◽

Vol 283 ◽

Cited By ~ 1

Author(s):

G. D. Sanders ◽

C. J. Stanton ◽

Y. C. Chang

Keyword(s):

Optical Properties ◽

Transport Properties ◽

Carrier Transport ◽

Phonon Scattering ◽

Quantum Wires ◽

Recent Observation ◽

Tight Binding ◽

Boltzmann Transport ◽

Electronic And Optical Properties ◽

Silicon Quantum Wires

ABSTRACTRecent observation of efficient luminescence in porous silicon has stimulated interest in the electronic and optical properties of Si quantum wires [1,2,3]. If silicon becomes a material suitable for optical applications, techniques for fabricating silicon wires reliably and uniformly will be needed. Once this is achieved, there will be interest not only in optical properties of silicon wires but also transport properties. For instance, to determine the properties of a hypothetical Si LED, one needs to know about both transport and optical properties.In this paper, we present theoretical studies of electronic, optical and transpon properties of silicon quantum wires ranging in size from 7.7Ä to 31Ä. The electronic and optical properties are treated in an empirical tight-binding approach with excitonic effects included in the effective mass approximation. Carrier transport is treated in a Boltzmann transport framework with nonpolar deformation potential acoustic phonon scattering being the dominant scattering mechanism.

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