Erratum: First-principles calculation of carrier-phonon scattering in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-type<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="bold">Si</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="bold">Ge</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>alloys [Phys. Rev

Murphy-Armando, Felipe; Fahy, Stephen

doi:10.1103/physrevb.86.079903

Cited by 21 publications

(37 citation statements)

References 9 publications

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“…17 Ab initio methods are powerful predictive tools that can compute the behavior of materials without the need of fitting parameters, allowing us to realize the concept of materials by design. 18 In our previous studies [13][14][15] we calculated the mobility of silicon germanium at all compositions and found excellent agreement with experiments. These calculations yielded previously unknown scattering and transport parameters that were used to predict the mobility in strained Ge 19 and strained SiGe alloys.…”

Section: Introductionmentioning

confidence: 82%

“…16 The intervalley and optical electron-phonon scattering is calculated with density functional perturbation theory, considering the effects of alloy disorder within the random mass approximation. 15,16 Alloy disorder scattering is calculated using the supercell approach and DFT as reported in Ref. 13.…”

Section: Calculation and Resultsmentioning

confidence: 99%

“…The acoustic electron-phonon scattering is calculated using density functional theory (DFT) and the frozen phonon method 15 accounting for the effects of strain on the matrix elements. 16 The intervalley and optical electron-phonon scattering is calculated with density functional perturbation theory, considering the effects of alloy disorder within the random mass approximation.…”

Section: Calculation and Resultsmentioning

confidence: 99%

“…In this work we use ab initio theoretical methods [13][14][15][16] to explore the parameter space in alloy composition, strain configuration, and current direction to determine the best possible strain gauge factors for single crystalline n-type bulk silicon-germanium alloys. We find ambient temperature gauge factors as high as G = 500, which are a factor of three larger than the maximum possible for single-crystalline silicon, and over five times that of germanium.…”

Section: Introductionmentioning

confidence: 99%

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Giant piezoresistance in silicon-germanium alloys

Murphy-Armando

Fahy

2012

Phys. Rev. B

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Type of publicationArticle (peer-reviewed) We use first-principles electronic structure methods to show that the piezoresistive strain gauge factor of single-crystalline bulk n-type silicon-germanium alloys at carefully controlled composition can reach values of G = 500, three times larger than that of silicon, the most sensitive such material used in industry today. At cryogenic temperatures of 4 K we find gauge factors of G = 135 000, 13 times larger than that observed in Si whiskers. The improved piezoresistance is achieved by tuning the scattering of carriers between different ( and L) conduction band valleys by controlling the alloy composition and strain configuration.

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Section: Introductionmentioning

confidence: 82%

Section: Calculation and Resultsmentioning

confidence: 99%

Section: Calculation and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Giant piezoresistance in silicon-germanium alloys

Murphy-Armando

Fahy

2012

Phys. Rev. B

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“…In photoexcited semiconductors, carrier relaxation occurs in a series of stages 8 : 1. momentum relaxation within a valley is dominated by electron-acousticphonon scattering in non-polar semiconductors 9,10 and by electron-LO-phonon scattering in polar semiconductors 11 but electron-electron scattering becomes much more competitive [12][13][14] than in metals (and in some twodimensional systems, carrier-carrier scattering may dominate 15 ). Compared to a metal, the difference in timescale between electron-phonon and electron-electron scattering is substantially reduced, because (a) the density of final states in the electron-phonon scattering process is substantially less than in a metal, thus reducing the electron-phonon scattering rate 8,16 and (b) screening of the Coulomb interaction is much less effective in the low-density semiconductor plasma than in a metal, so that carrier-carrier scattering at small momentum transfer (i.e.…”

Section: Introductionmentioning

confidence: 99%

Free-carrier relaxation and lattice heating in photoexcited bismuth

et al. 2013

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We report ultrafast surface pump and interface probe experiments on photoexcited carrier transport across single crystal bismuth films on sapphire. The film thickness is sufficient to separate carrier dynamics from lattice heating and strain, allowing us to investigate the time-scales of momentum relaxation, heat transfer to the lattice and electron-hole recombination. The measured electron-hole (e − h) recombination time is 12-26 ps and ambipolar diffusivity is 18-40 cm 2 /s for carrier excitation up to ∼ 10 19 cm −3 . By comparing the heating of the front and back sides of the film, we put lower limits on the rate of heat transfer to the lattice, and by observing the decay of the plasma at the back of the film, we estimate the timescale of electron-hole recombination. We interpret each of these timescales within a common framework of electron-phonon scattering and find qualitative agreement between the various relaxation times observed. We find that the carrier density is not determined by the e − h plasma temperature after a few picoseconds. The diffusion and recombination become nonlinear with initial excitation > ∼ 10 20 cm −3 .

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Accelerated Screening of Thermoelectric Materials by First‐Principles Computations of Electron–Phonon Scattering

Samsonidze

Kozinsky

2018

Advanced Energy Materials

128

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Recent discoveries of new materials for thermoelectric energy conversion are enabled by efficient prediction of the materials' performance from first-principles, without empirically fitted parameters. The novel simplified approach for computing electronic transport properties is described, which achieves good accuracy and transferability while greatly reducing complexity and computation cost compared to the existing methods. The first-principles calculations of the electron-phonon coupling demonstrate that the energy dependence of the electron relaxation time varies significantly with chemical composition and carrier concentration, suggesting that it is necessary to go beyond the commonly used approximations to screen and optimize materials' composition, carrier concentration, and microstructure. The new method is verified using high accuracy computations and validated with experimental data before applying it to screen and discover promising compositions in the space of half-Heusler alloys. By analyzing data trends the effective electron mass is identified as the single best general descriptor determining material' performance. The Lorenz number is computed from first principles and the universality of the Wiedemann-Franz law in thermoelectrics is discussed.

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Erratum: First-principles calculation of carrier-phonon scattering inn-typeSi1−xGexalloys [Phys. Rev

Cited by 21 publications

References 9 publications

Giant piezoresistance in silicon-germanium alloys

Giant piezoresistance in silicon-germanium alloys

Free-carrier relaxation and lattice heating in photoexcited bismuth

Accelerated Screening of Thermoelectric Materials by First‐Principles Computations of Electron–Phonon Scattering

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