Electron-acoustic phonon scattering in SiO2 determined from a pseudo-potential for energies of E≳E
 BZ

Bradford, J. N.; Woolf, S.

doi:10.1063/1.350254

Cited by 35 publications

(17 citation statements)

References 11 publications

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“…The electron thermalization time increases roughly inversely with optical phonon frequency, and was found to be about 7 ps in CsI, 2 ps in NaI, and 0.5 ps in CaF 2 16. Assuming a hot‐electron velocity distribution given by a parabolic band‐edge effective mass model in the first Brillouin zone, with approximate corrections applied in outer zones 5, 20, 21, the resulting step size and thermalization time yielded the hot‐electron ranges mentioned above 5, 16. This dramatic difference between the hot‐electron thermalization range and the restricted range of self‐trapped holes produces charge separation such as discussed in the thermalized model above, but substantially more because the hot‐electron diffusion is less sensitive to electric field attraction toward the track core of self‐trapped holes.…”

Section: Discussionmentioning

confidence: 99%

The roles of thermalized and hot carrier diffusion in determining light yield and proportionality of scintillators

Grim

Üçer

et al. 2012

Physica Status Solidi (a)

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Numerical modeling and comparison to experiment in the materials for which suitable parameters have been measured confirm that three of the most important material parameters for predicting proportionality and the related host‐dependent light yield (LY) of scintillators are (i) the carrier diffusion coefficients (including hole self‐trapping if present, and hot‐electron diffusion if unthermalized), (ii) the kinetic order and associated rate constant of nonlinear quenching, and (iii) deep‐trapping probability. Thermalized carrier diffusion appears sufficient to describe the main trends in oxides and semiconductors. For heavier halide hosts, it appears necessary to take account of hot‐electron diffusion to explain several important host‐dependent trends.

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Section: Discussionmentioning

confidence: 99%

The roles of thermalized and hot carrier diffusion in determining light yield and proportionality of scintillators

Grim

Üçer

et al. 2012

Physica Status Solidi (a)

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“…first introduced by Bradford and Woolf, 40 in which α is the screening correction factor, was added into the integrand of the acoustic phonon-particle scattering rate described by Sparks et al 36 to correct for the fact that the calculated scattering rates become unphysical as the particle energy increases beyond the energy of the first Brillouin zone. We used the same approach used by Bradford and Woolf to determine the value of α, i.e.…”

Section: Electron/hole Scattering Rates and Angles From Phononsmentioning

confidence: 99%

Radiation response of inorganic scintillators: insights from Monte Carlo simulations

Prange

Xie

et al. 2014

SPIE Proceedings

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The spatial and temporal scales of hot particle thermalization in inorganic scintillators are critical factors determining the extent of second-and third-order nonlinear quenching in regions with high densities of electron-hole pairs, which, in turn, leads to the light yield nonproportionality observed, to some degree, for all inorganic scintillators. Therefore, kinetic Monte Carlo simulations were performed to calculate the distances traveled by hot electrons and holes as well as the time required for the particles to reach thermal energy following γ-ray irradiation. CsI, a common scintillator from the alkali halide class of materials, was used as a model system. Two models of quasi-particle dispersion were evaluated, namely, the effective mass approximation model and a model that relied on the group velocities of electrons and holes determined from band structure calculations. Both models predicted rapid electron-hole pair recombination over short distances (a few nanometers) as well as a significant extent of charge separation between electrons and holes that did not recombine and reached thermal energy. However, the effective mass approximation model predicted much longer electron thermalization distances and times than the group velocity model. Comparison with limited experimental data suggested that the group velocity model provided more accurate predictions. Nonetheless, both models indicated that hole thermalization is faster than electron thermalization and thus is likely to be an important factor determining the extent of third-order nonlinear quenching in high-density regions. The merits of different models of quasi-particle dispersion are also discussed.

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“…It has long been speculated that this would necessitate a full quantum description of the transport process. Alternatively, Bradford and Woolf [12] showed that the introduction of screening into the electron-acoustic-phonon interaction could reproduce the photoemission data quantitatively, without abandoning the semiclassical formalism. In this Letter we shall demonstrate experimentally that the discrepancy between the semiclassical Monte Carlo model and the photoemission results at kinetic energies > 6 eV is far more serious than a discrepancy in specific rates.…”

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confidence: 98%

Breakdown of the semiclassical description of hot-electron dynamics inSiO2

Eklund¹,

McFeely²,

Cartier³

1992

Phys. Rev. Lett.

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Soft-x-ray photoemission measurements of the bulk Si 2p core level in Si/Si02 overlayer structures show that hot-electron transport in SiC>2 is essentially independent of temperature between 300 and 980 K. These results reveal a basic failure of the semiclassical Monte Carlo formalism to correctly model the strong electron-phonon interaction in SiC>2 at electron energies > 6 eV. The experimental data are shown to be consistent with the trends seen in quantum Monte Carlo transport calculations.PACS numbers: 72.20.Dp, 72.80.Ng, 79.60.Eq Gaining a fundamental understanding of the processes which lead to the degradation of insulators, such as hotelectron-induced bond breaking [1] and impact ionization [2,3], has been an important goal for the physics of semiconductor devices. Accordingly, major efforts, both experimental [4] and theoretical [5], have been undertaken in order to understand the dynamics of hot electrons in SiC>2. Fischetti [5] and co-workers have provided a conceptual framework for the understanding of a large body of high-field transport experiments by means of semiclassical Monte Carlo transport simulations which include both polar and acoustic electron-phonon scattering. The impressive record of agreement with experiment [2-4, 6-10] has made the semiclassical Monte Carlo formalism a widespread standard methodology for the analysis of hot-electron transport experiments in S1O2 [11-13].The recent development of zero-field photoemissionbased techniques has allowed direct measurements of absolute electron-phonon scattering rates over a wide energy range [14-16]. These measurements revealed problems with a straightforward application of this standard model at electron energies larger than 6 eV. Instead of continuing to increase, as predicted by the deformation-potential matrix elements, the acoustic phonon scattering, the key mechanism for the stabilization of the electron distribution under high-field stress, was shown to be almost constant in rate between 8 and 20 eV [15,16].The underlying physical reason for this discrepancy was unclear. The strong coupling between the hot electrons and the lattice at high energies leads to extremely short quasiparticle lifetimes. It has long been speculated that this would necessitate a full quantum description of the transport process. Alternatively, Bradford and Woolf [12] showed that the introduction of screening into the electron-acoustic-phonon interaction could reproduce the photoemission data quantitatively, without abandoning the semiclassical formalism. In this Letter we shall demonstrate experimentally that the discrepancy between the semiclassical Monte Carlo model and the photoemission results at kinetic energies > 6 eV is far more serious than a discrepancy in specific rates. Rather, it signals the breakdown of the entire semiclassical formalism itself and the onset of a strong quantum transport regime. The evidence for this transition comes from the temperature dependence of the transport process. The strong temperature dependence implicit in the semicl...

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Electron-acoustic phonon scattering in SiO2 determined from a pseudo-potential for energies of E≳E BZ

Cited by 35 publications

References 11 publications

The roles of thermalized and hot carrier diffusion in determining light yield and proportionality of scintillators

The roles of thermalized and hot carrier diffusion in determining light yield and proportionality of scintillators

Radiation response of inorganic scintillators: insights from Monte Carlo simulations

Breakdown of the semiclassical description of hot-electron dynamics inSiO2

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