ESE 521 S19 Kagan Problem Set 5.pdf - University of Pennsylvania ESE 521 Semiconductor Device Physics and Technology Due Prof C R Kagan Homework#5 1 A

ESE 521 S19 Kagan Problem Set 5.pdf - University of...

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University of Pennsylvania ESE 521 Semiconductor Device Physics and Technology Due: April 17, 2019 Prof. C. R. Kagan Homework #5 1. A photoconductor with dimensions L= 6 mm, W=2 mm, and D=1 mm is placed under uniform radiation. The absorption of the light increases the current by 2.83 mA. A voltage of 10 V is applied across the device. As the radiation is suddenly cut off, the current falls, initially at a rate of 23.6 A/s. The electron and hole mobility are 3600 and 1700 cm 2 /Vs, respectively. Find: a. The equilibrium density of electron-hole pairs generated under radiation b. The minority-carrier lifetime c. The excess density of electrons and holes remaining 1 ms after the radiation is cut off. 2. Find the maximum responsivity of an ideal (unity quantum efficiency and unity gain) semiconductor photodetector made of (a) Si, (b) GaAs, and (c) InSb. 3. Consider a silicon p-n junction solar cell of area 2 cm 2 . If the dopings of the solar cell are N A =1.7 x 10 16 /cm 3 and N D =5 x 10 19 /cm 3 , and given τ n = 10 µ s, τ p = 0.5 µ s, D n = 9.3 cm 2 /s, D p = 2.5 cm 2
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