# HW4 - Georgia Institute of Technology School of Electrical and Computer Engineering ECE 3040A Homework 4 Due Friday in class 1(25 points(a Show

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Georgia Institute of Technology School of Electrical and Computer Engineering ECE 3040A Homework 4 Due: Friday 09/19/2008 in class 1. (25 points) (a) Show that the minimum conductivity of a semiconductor sample occurs when n p i n n µ / 0 = . Hint: Use 2 i n np = . (b) What is the expression for minimum conductivity σ min . (c) Find σ min for Si at T=300 K, and compare it with intrinsic conductivity of Si. Use n i = 10 10 cm -3 , µ n = 1360 cm 2 /(V.sec), and µ p = 460 cm 2 /(V.sec) for Si at 300 K. 2. (15 points) Assume that for a specific semiconductor material, both electron and hole mobilities vary with temperature as T -3/2 in the temperature range of impractical interest. Explain whether conductivity increases or decreases with
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## This note was uploaded on 01/17/2011 for the course ECE 3040 taught by Professor Hamblen during the Fall '07 term at Georgia Institute of Technology.

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