Transport and Deformation-Potential Theory for Many-Valley Semiconductors with Anisotropic Scattering

Herring, Conyers; Vogt, Erich

doi:10.1103/physrev.101.944

Cited by 1,307 publications

(458 citation statements)

References 25 publications

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“…The energy relaxation is enabled by phonons, whereas spin-orbit interactions allow for a spin flip. In a (001)-grown quantum well of silicon, the electron-phonon coupling for intravalley scattering is the deformation potential of transverse acoustic (TA) and longitudinal acoustic (LA) phonons, given by 60,64,[81][82][83][84] …”

Section: Modelmentioning

confidence: 99%

Theory of spin relaxation in two-electron laterally coupled Si/SiGe quantum dots

2012

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Highly accurate numerical results of phonon-induced two-electron spin relaxation in silicon double quantum dots are presented. The relaxation, enabled by spin-orbit coupling and the nuclei of 29 Si (natural or purified abundance), is investigated for experimentally relevant parameters, the interdot coupling, the magnetic field magnitude and orientation, and the detuning. We calculate relaxation rates for zero and finite temperatures (100 mK), concluding that our findings for zero temperature remain qualitatively valid also for 100 mK. We confirm the same anisotropic switch of the axis of prolonged spin lifetime with varying detuning as recently predicted in GaAs. Conditions for possibly hyperfine-dominated relaxation are much more stringent in Si than in GaAs. For experimentally relevant regimes, the spin-orbit coupling, although weak, is the dominant contribution, yielding anisotropic relaxation rates of at least two orders of magnitude lower than in GaAs.

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Section: Modelmentioning

confidence: 99%

Theory of spin relaxation in two-electron laterally coupled Si/SiGe quantum dots

2012

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“…50 We introduce the HerringVogt transformation defined by k * i = T n ij k n i . 54 In the frame of reference of the n th valley, centered at the bottom of the valley with the z axis along its symmetry axis, we take the transformation matrix T n = diag m 0 /m t , m 0 /m t , m 0 /m l so that the ellipsoidal constant energy surfaces become spheres. To preserve vector equations, T n is also applied to other vector quantities such as phonon wavevectors.…”

Section: A Photoluminescence In Germaniummentioning

confidence: 99%

Spin and energy relaxation in germanium studied by spin-polarized direct-gap photoluminescence

et al. 2013

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Spin orientation of photoexcited carriers and their energy relaxation is investigated in bulk Ge by studying spin-polarized recombination across the direct band gap. The control over parameters such as doping and lattice temperature is shown to yield high polarization degree, namely larger than 40%, as well as a fine-tuning of the angular momentum of the emitted light with a complete reversal between right-and left-handed circular polarization. By combining the measurement of the optical polarization state of band-edge luminescence and Monte Carlo simulations of carrier dynamics, we show that these very rich and complex phenomena are the result of the electron thermalization and cooling in the multi-valley conduction band of Ge. The circular polarization of the direct-gap radiative recombination is indeed affected by energy relaxation of hot electrons via the X valleys and the Coulomb interaction with extrinsic carriers. Finally, thermal activation of unpolarized L valley electrons accounts for the luminescence depolarization in the high temperature regime.

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“…1,2 However, the thermoelectric power factor, which characterizes the electrical properties, is known to be a function of effective mass (m*) and mobility (m) 1,3-5 via the weighted mobility 3,4,6,7 (S 2 /r f m* 1.5 m). A further consideration of multi-valley band systems and carrier scattering by acoustic vibrations, [8][9][10] as found in most efficient thermoelectrics at temperatures where zT peaks, reveals that large number of valleys (N v ) 3,4,11,12 and low conduction mass (m c *) are beneficial for thermoelectric performance (S 2 /r f N v /m c *). 3,4,[13][14][15] In spite of the low degeneracy, it has long been known that narrow band gap G-semiconductors (N v ¼ 1) such as InSb and InAs contain a power factor as high or even higher 16,17 than those of known high degeneracy n-type thermoelectrics 18 (N v $ 4), because of the extremely low effective masses (#0.05m e , where m e is the free electron mass).…”

Section: Introductionmentioning

confidence: 99%

Alloying to increase the band gap for improving thermoelectric properties of Ag2Te

2011

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Ag 2 Te simultaneously shows high mobility and low thermal conductivity, however the relatively low band gap of $0.2 eV prevents it from achieving high thermoelectric figure of merit, zT, in the high temperature phase. In this study, the band gap of Ag 2 Te has been increased enabling a zT of unity by forming alloys and composites with PbTe, thereby demonstrating the importance of exploiting potentially good thermoelectrics among these small band gap semiconductors and similar materials.

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Transport and Deformation-Potential Theory for Many-Valley Semiconductors with Anisotropic Scattering

Cited by 1,307 publications

References 25 publications

Theory of spin relaxation in two-electron laterally coupled Si/SiGe quantum dots

Theory of spin relaxation in two-electron laterally coupled Si/SiGe quantum dots

Spin and energy relaxation in germanium studied by spin-polarized direct-gap photoluminescence

Alloying to increase the band gap for improving thermoelectric properties of Ag2Te

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