Exchange effects in hot plasmas in semiconductors

Kriman, A. M.; Joshi, R. P.; Kann, M. J.; Ferry, D. K.

doi:10.1088/0268-1242/7/3b/058

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…27,33 In addition, MD has been extended to describe the exchange interaction among indistinguishable electrons. [28][29][30] Previous work combining classical MD with a quasielectrostatic grid-based field solver (such as an iterative solver of Poisson's equation) divides the Coulomb interaction into a short-range component, which describes interactions among particles separated by distances shorter than a couple of grid cells, and a long-range component. 25,26,32 The long-range part of the Coulomb interaction is quickly and accurately described by the field solver, and the short-range part is described by MD.…”

Section: Molecular Dynamics (Md)mentioning

confidence: 99%

“…As n 0 increases, the exchange interaction among indistinguishable particles increasingly impacts materials properties. [28][29][30]41 The exchange interaction is a geometric consequence of the Pauli exclusion principle that manifests itself as a reduction in the force among indistinguishable electrons. [28][29][30]39 We adopt the formulation of Refs.…”

Section: Exchange Interactionmentioning

confidence: 99%

“…25,26 At carrier densities above 10 19 cm À3 , the exchange interaction among indistinguishable electrons, and the correlation effect between all electrons, can significantly affect bulk materials properties as well. 12,[27][28][29][30] Molecular dynamics (MD) has the ability to capture Coulomb interactions on subgrid-cell length scales. 25,27,[31][32][33] In this paper, we describe the EMC=FDTD=MD technique for THz-frequency materials characterization of semiconductors and metals.…”

Section: Introductionmentioning

confidence: 99%

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Multiphysics simulation of high-frequency carrier dynamics in conductive materials

Willis

Hagness

Knežević

2011

Journal of Applied Physics

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We present a multiphysics numerical technique for the characterization of high-frequency carrier dynamics in high-conductivity materials. The technique combines the ensemble Monte Carlo (EMC) simulation of carrier transport with the finite-difference time-domain (FDTD) solver of Maxwell's curl equations and the molecular dynamics (MD) technique for short-range Coulomb interactions (electron-electron and electron-ion) as well as the exchange interaction among indistinguishable electrons. We describe the combined solver and highlight three key issues for a successful integration of the constituent techniques: (1) satisfying Gauss's law in FDTD through proper field initialization and enforcement of the continuity equation, (2) avoiding double-counting of Coulomb fields in FDTD and MD, and (3) attributing finite radii to electrons and ions in MD for accurate calculation of the short-range Coulomb forces. We demonstrate the strength of the EMC=FDTD=MD technique by comparing the calculated terahertz conductivity of doped silicon with available experimental data for two doping densities and showing their excellent agreement. V

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Section: Molecular Dynamics (Md)mentioning

confidence: 99%

Section: Exchange Interactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiphysics simulation of high-frequency carrier dynamics in conductive materials

Willis

Hagness

Knežević

2011

Journal of Applied Physics

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“…Changes arise, however, because the total energy H(fai,xj,pi}1) (PI'4'I'). (10) has exchange components. Specifically, if we assume a parabolic band with mass m, and a translationinvariant spin-independent pair potential V(r-r'), then the semiclassical Hamiltonian consists of kinetic energy, direct Coulomb, and exchange interaction parts H=EK+ED+EXC (11) which may be written The mass m appearing in (12a) is taken as the local mass of the valley corresponding to the particular k. In practice, we use a a valley index, and approximate the exchange interaction of electrons outside the F valley to zero, since the k-space distances are small only in the central valley.…”

Section: Semiclassical Equations Of Motionmentioning

confidence: 99%

Many-body semiclassical approximation for semiconductor plasmas

1992

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Realistic simulations of semiconductor plasmas require detailed, many-species descriptions of the phonon and electronic systems. Limited numerical power then usually requires simplifying approximations. One approximation is the use of a screened Coulomb interaction. When an accurate screening function is not available, or when a better electrostatics treatment is needed, one can perform ensemble Monte Carlo (EMC) simulations that use a phase-space-trajectories or "molecular dynamics" (MD) evolution of the electron ensemble. In these EMCIMD simulations, Coulomb scattering events are treated continuously in the MD evolution of electron trajectories rather than by instantaneous scattering in EMC. Dynamic screening effects are then included accurately by the explicit correlated motion of the electron ensemble. The electron trajectories simulated by MD have until recently been completely classical. We describe extensions of EMCTMD into the semiclassical regime, thus incorporating quantum effects such as position-momentum uncertainty. The method takes account of the Fermi statistics of the many-electron ensemble, yielding spin-dependent exchange contributions to the forces and effective mass. We describe effects of these corrections on the velocity autocorrelation function and on thermalization of satellite-valley electrons.

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A generalized Drude model for doped silicon at terahertz frequencies derived from microscopic transport simulation

Willis

Hagness

Knežević

2013

Applied Physics Letters

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Unveiling the full potential of doped silicon for electronic, photonic, and plasmonic application at THz frequencies requires a thorough understanding of its high-frequency transport properties. In this letter, we present a comprehensive numerical characterization of the frequency-dependent (0–2.5 THz) complex conductivity of silicon at room temperature over a wide range of doping densities (1014−1018 cm−3). The conductivity was calculated using a multiphysics computational technique that self-consistently couples ensemble Monte Carlo (EMC) simulation of carrier transport, the finite-difference time-domain (FDTD) solution to Maxwell's equations, and molecular dynamics (MD) for the treatment of short-range Coulomb interactions. Our EMC/FDTD/MD numerical results complement the experimental data that only exist for a select few doping densities. Moreover, we show that the computed complex conductivity of Si at THz frequencies can be accurately described by a generalized Drude (GD) model with doping-dependent parameters that capture the cross-over from phonon-dominated to Coulomb-dominated electron transport as the doping density increases. The simplicity of the GD model enables one to readily compute the complex conductivity of silicon for any doping density within the range studied here.

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Exchange effects in hot plasmas in semiconductors

Cited by 5 publications

References 16 publications

Multiphysics simulation of high-frequency carrier dynamics in conductive materials

Multiphysics simulation of high-frequency carrier dynamics in conductive materials

Many-body semiclassical approximation for semiconductor plasmas

A generalized Drude model for doped silicon at terahertz frequencies derived from microscopic transport simulation

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