L25_Phonon Scattering III

L25_Phonon Scattering III - ECE-656: Fall 2009 Lecture 25:...

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Lundstrom ECE-656 F09 ECE-656: Fall 2009 Lecture 25: Phonon Scattering III Professor Mark Lundstrom Electrical and Computer Engineering Purdue University, West Lafayette, IN USA 1 Lundstrom ECE-656 F09 2 outline 1) Review 2) POP and IV scattering 3) Scattering in common semiconductors 4) Electron-electron scattering 5) Summary
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Lundstrom ECE-656 F09 3 electron-phonon scattering S p , p ( ) = 2 π H p , p 2 δ E E   ω ( ) (weak scattering) H p , p 2 = 1 Ω K β 2 2 ρω N + 1 2 1 2 p , p ± N = 1 e k B T 1 Isotropic: no β dependence in the matrix element. Elastic: approximately elastic when << E p ( ) p p α E = E ± p = p ± Lundstrom ECE-656 F09 4 ADP scattering S p , p ( ) 2 H p , p 2 E E ( ) (ABS + EMS) H p , p 2 = 1 Ω K 2 2 N + 1 2 1 2 p , p ± N = 1 e k B T 1 k B T K 2 = 2 D A 2 1 τ = 2 D A 2 k B T c l D 3 D E ( ) 2 1 = 1 m (isotropic) (Nearly elastic at room temperature) E 1 1 E
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Lundstrom ECE-656 F09 5 ODP scattering S p , p ( ) 2 π H p , p 2 δ E E ± ω 0 ( ) H p , p 2 = 1 Ω K β 2 2 ρω N 0 + 1 2 1 2 p , p ± N 0 = 1 e k B T 1 < N 0 + 1 1 τ = 1 m (isotropic) (inelastic at RT and below) 1 = 2 D O 2 2 0 N 0 + 1 2 1 2 D 3 D E ± 0 ( ) 2 1 abs 1 ems K 2 = D 0 2 E 1 0 (EMS ABS Lundstrom ECE-656 F09 6 outline 1) Review 2) POP and IV scattering 3) Scattering in common semiconductors 4) Electron-electron scattering 5) Summary
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1 τ > 1 m > 1 E 1 = 1 abs + 1 ems = q 2 ω 0 2 κ 0 1 2 πκ 0 ε 0 2 E m * N 0 sinh 1 E 0 + N 0 + 1 ( ) sinh 1 E 0 1 See Lundstrom, pp. 84 – 86 for momentum and energy relaxation rates. 7 POP scattering S p , p ( ) 2 π H p , p 2 δ E E ± 0 ( ) H p , p 2 = 1 Ω K β 2 2 ρω N 0 + 1 2 1 2 p , p ± N 0 = 1 e 0 k B T 1 < N 0 + 1 (inelastic at RT and below) K 2 = ρ q 2 0 2 2 0 0 0 1 (favors small angle scattering) Lundstrom ECE-656 F09 8 POP scattering E 1 0 ABS + EMS ABS 10 13 10 12 1 1 m possibility of “polar runaway” 0 34 meV (GaAs) 1 0 1 2 *
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Requires phonons with momentum near the zone boundary.
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This note was uploaded on 11/01/2009 for the course PSY 120 taught by Professor Donnely during the Spring '08 term at Purdue University-West Lafayette.

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L25_Phonon Scattering III - ECE-656: Fall 2009 Lecture 25:...

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