Electron-electron interactions, coupled plasmon-phonon modes, and mobility in n-type GaAs
This paper investigates the mobility of electrons scattering from the coupled system of electrons and longitudinal optical (LO) phonons in n-type GaAs. The Boltzmann equation is solved exactly for low electric fields by an iterative method, including electron-electron and electron-LO phonon scatteri...
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Zusammenfassung: | This paper investigates the mobility of electrons scattering from the coupled
system of electrons and longitudinal optical (LO) phonons in n-type GaAs. The
Boltzmann equation is solved exactly for low electric fields by an iterative
method, including electron-electron and electron-LO phonon scattering
dynamically screened in the random-phase-approximation (RPA). The LO phonon
self-energy is treated in the plasmon-pole approximation. Scattering from
ionized impurities screened in static RPA is calculated with phase-shift cross
sections, and scattering from RPA screened deformation potential and
piezoelectric acoustic phonons is included in the elastic approximation. The
results show that dynamic screening and plasmon-phonon coupling significantly
modify inelastic scattering at low temperatures and densities. The effect on
mobility is obscured by ionized impurity scattering in conventionally doped
material, but should be important in modulation doped structures. For
uncompensated bulk n-type GaAs, the RPA phase-shift model for electron-impurity
scattering gives lower drift mobilities than the standard Thomas-Fermi or Born
calculations which are high compared to experiment. Electron-electron
scattering lowers the mobility further, giving improved agreement with
experiment though discrepancies persist at high donor concentrations
($n>10^{18}{\rm cm}^{-3}$). When impurities are ignored, inelastic scattering
from the coupled electron-phonon system is the strongest scattering mechanism
at 77 K for moderate doping. This result differs from the standard model
neglecting mode coupling and electron-electron scattering which has the
acoustic modes dominant in this regime. |
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DOI: | 10.48550/arxiv.cond-mat/9501084 |