ECE 3150 Spring 2009 Week 5 Recitation Ask for Homework questions first on Homework 4. Spend some good time on it. If there is no question, walk through Question 2 step by step, and ask them how they will approach the problem. This is the time students can get lost, but should not. Draw a PNP with N E = 10 20 cm-3 , N B = 10 17 cm-3 and N C = 10 16 cm-3 . 1. Ask the students to draw the hole concentration in the forward active mode, in both linear and log scales. 2. What additional information is needed for calculating I E , I B , and I C ? Separate the needed parameters into: material constants (mobility or diffusivity; relaxation time (not needed if collector efficiency is given) device geometry: L B (why is L E and L C not needed) and A . Ebers-Moll model: I F , α F and V A . Electrical bias: V BE (why V BC or V CE is not needed). 3. How are I F , F and V A related to the material constants and device geometry? 4.
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