Lecture10(2)

N glight r no po n rn using 2 negligible 1 r no

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Unformatted text preview: nority Carrier Concentration Low Injection EE 332 Spring 2013 Recombinations Direct recombination Indirect recombination Trapping Photoluminescence Electroluminescence (LED Ch. 8) EE 332 Spring 2013 Generation-Recombination Equilibrium Generation-Recombination Equilibrium EE 332 Spring 2013 Direct Recombination Direct Recombination EE 332 Spring 2013 Recombination Lifetime (Special Case ) Recombination Lifetime (n0 p0 ) n Low-level Injection: Excess EHP is much smaller than the majority carrier dδ n( t ) = −α r " n0 + p0 δ n( t )$ # % dt ( ) GLight r no po n rn 2 negligible 1 r no po Using: GLight Under low-level excitation: n n ECE 440: Mohamed Mohamed EE 332 Spring 2013 How Does n and p Change with Light? How Does n and p Change with Light? Constant light illumination: n no n p po p Shining a light creates an equal number of Excess Electron-hole pair Light is turned off at t=0: t n(t ) no ne t 0 n p(t ) po pe t n n p ECE 440: Mohamed Mohamed EE 332 Spring 2013 Recombination Dynamics Recombination Dynamics -t/τn EE 332 Spring 2013 Carrier Concentration Change Carrier Concentration Change EE 332 Spring 2013 Photo-conductivity q n0 n n po p p Photo-Conductivity q n0Carrier Lifetime p p n n po q nn p p q nn p p At Low level: q nGlight n pGlight p At Low level: q nGlight n pGlight p ECE 440: Mohamed Mohamed ECE 440: Mohamed Mohamed EE 332 Spring 2013 Re-define Mass Action Law Example: Quasi-Fermi Levels EE 332 Spring 2013 ffect of shining light on energy...
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This document was uploaded on 02/18/2014.

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