The net number of electrons passing from left to

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Unformatted text preview: depend upon \me (t) unless the device or material is under steady- state condi\ons no(K)+δn(x) Ÿ༉ Ÿ༉ Ÿ༉ t Ei EF Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ Ÿ༉ po(K)+δp(x) n = ni e( Fn ( x ,t )− Ei )/kT E − F ( x ,t ) / kT p = n e( i p ) i Ÿ༉ Photoconduc\vity Conductivity: σ = q(nµn + pµ p ) = q(no + δ n )µn + q( po + δ p )µ p = q(no µn + po µ p ) + q(δ nµn + δ pµ p ) = σ o + Δσ Photoconductivity Change: Δσ = q(δ nµn + δ pµ p ) = qgopt (τ n µn + τ p µ p ) Since δ n = goptτ n and δ p = goptτ p •  Maximizing Δσ: –  Large mobility –  Long carrier life\me •  Other comments: –  Photon energy higher than bandgap, but not by too much 18 Illustra\on of Diffusion 20 Diffusion Diffusion: Net Mo\on & Slope Negative Slope: Net particle motion in positive direction Ÿ༉ Diffusion: Net Current Negative Slope: Net particle motion in positive direction Ÿ༉ + Positive charge, positive current Diffusion: Net Current Negative Slope: Net particle motion in positive direction Ÿ༉ - Negative charge, negative current Diffusion: Net Mo\on & Slope Positive Slope: Net particle motion in negative direction Ÿ༉ Diffusion:...
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This note was uploaded on 03/06/2014 for the course ECE 340 taught by Professor Leburton during the Spring '11 term at University of Illinois, Urbana Champaign.

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