Practice Final

# Practice Final - Problem 1 (25 points) Consider a silicon...

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1 Problem 1 (25 points) Consider a silicon pn junction with a cross-sectional area of 10 -4 cm 2 and the following parameters at T = 300K: 17 3 15 3 7 6 10 , 5 10 , 10 , 10 N cm N x cm s s d a p n  22 400 / . , 1000 / . pn cm V s cm V s   a) (10 points) Sketch the thermal-equilibrium energy-band diagram across the pn junction. b) (5 points) Determine the ratio of the hole current to total current at the space charge edge x n c) (5 points) Determine the ratio of the electron current to total current at the space charge edge -x p d) (5 points) Calculate the total number of excess electrons in the p region for V a =0.5V

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2 Problem 2 (25 points) Consider an Si pnp transistor with N E = 2x10 17 cm -3 , N B = 2x10 16 cm -3 , N C = 2x10 15 cm -3 . The metallurgical base width is 1 m and the base cross sectional area is 10 m 2 . Assume the critical field to be equal to 10 5 V/cm. 2 10 14 1.5 10 , 11.7 78.854 10 / i s n x cm x x F cm  a) (5 points) Draw the energy band diagram under equilibrium.
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## This note was uploaded on 10/03/2010 for the course ESE 231 taught by Professor Kamoua,r during the Spring '08 term at SUNY Stony Brook.

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Practice Final - Problem 1 (25 points) Consider a silicon...

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