MSE+302+Problem+Set+2

MSE+302+Problem+Set+2 - MSE 302 1. Due Friday, April 25th...

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MSE 302 Problem Set 2 Due Friday, April 25 th 1. Consider radiative, defect and Auger recombination for a p-type doped piece of Si: a. Write an expression for the total recombination lifetime when all of these mechanisms are occurring. Assume the defect recombination lifetime, τ d , does not depend on carrier concentrations. b. For recombination rate coefficients s s cm s cm d Aug rad 5 1 6 30 1 3 13 10 5 . 4 and , 10 3 , 10 - - - - - × = × = = τ α , at what doping density does Auger recombination become dominant? c. Using the coefficients above and the mobility data for silicon (page 99, Streetman), calculate the minority carrier diffusion length for doping densities of 10 15 cm -3 and 10 19 cm - 3 . 2. Below is the absorption spectrum for GaAs. Let’s assume the bandgap is exactly 900nm. The units for absorption are in inverse microns but that is not important for this problem. The relative absorption strength as a function of wavelength may be important, however. This exercise should help you build some intuition for the meaning behind the external quantum efficiency (EQE) of a solar cell. Absorption Spectrum of GaAs 0 10 20 30 40 50 60 70 80 400 416 432 448 464 480 496 512 528 544 560 576 592 608 624 640 656 672 688 704
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This note was uploaded on 12/01/2011 for the course MS&E 302 taught by Professor Mcghee during the Spring '08 term at Stanford.

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MSE+302+Problem+Set+2 - MSE 302 1. Due Friday, April 25th...

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