First principles calculation of electron-phonon and alloy scattering in strained SiGe

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Murphy-Armando, Felipe
Fahy, Stephen B.
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American Institute of Physics Publishing
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First-principles electronic structure methods are used to predict the mobility of n-type carrier scattering in strained SiGe. We consider the effects of strain on the electron-phonon deformation potentials and the alloy scattering parameters. We calculate the electron-phonon matrix elements and fit them up to second order in strain. We find, as expected, that the main effect of strain on mobility comes from the breaking of the degeneracy of the six Δ and L valleys, and the choice of transport direction. The non-linear effects on the electron-phonon coupling of the Δ valley due to shear strain are found to reduce the mobility of Si-like SiGe by 50% per % strain. We find increases in mobility between 2 and 11 times that of unstrained SiGe for certain fixed Ge compositions, which should enhance the thermoelectric figure of merit in the same order, and could be important for piezoresistive applications.
Electron mobility , Shear deformation , Electron-phonon interactions , Point defect scattering , Conduction bands , Ab initio calculations , Semiconductor materials , Ge-Si alloys , Seebeck effect
MURPHY-ARMANDO, F. & FAHY, S. B. 2011. First principles calculation of electron-phonon and alloy scattering in strained SiGe. Journal of Applied Physics, 110, 123706. doi:10.1063/1.3669446
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