EMS172-2009-Homework8+%2B+solutions - UNIVERSITY OF...

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EMS 172 Profs. Y. Takamura and A. Moulé, 2008 UNIVERSITY OF CALIFORNIA, DAVIS Department of Chemical Engineering and Materials Science EMS 172: Electronic, Magnetic, and Optical Properties of Materials Homework 8 Due Date: Thursday, Dec. 3 rd , 2009 in class Note: You must show all the steps you used to obtain your answer in order to receive full credit. You have a new job for a photovoltaics company. Your new boss wants you to work on an optical model for the purpose of comparing Si and GaAs based solar cells. You are given measured optical parameters (nkSi.txt and GaAs.txt) and asked to write a program to calculate the following. Hint: you can save your output variables to ascii files using the command “save” see help 1. 10 pts Plot comparative graphs of refractive index (linear) and extinction coefficient (semilogy) for Si and GaAs. Be sure to label axis and provide a legend (that can be read in black/white). Describe what features, if any, differentiate the optical properties of the two materials. Plot 7 pts Correct scales 2 Legends 1 Titles 1 Data 3 Explanation 3 pts Direct/indirect 2 Extinction coefficient 1 There are two differences. First, GaAs has a much higher extinction coefficient throughout most of the visible and near IR. Second, GaAs is a direct semiconductor while Si is an indirect semiconductor. This can be seen in that the k for Si slowly declines over a large energy range while the GaAs has a sudden cutoff.
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This note was uploaded on 05/14/2010 for the course EMS 172 taught by Professor Takamura during the Winter '10 term at UC Davis.

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EMS172-2009-Homework8+%2B+solutions - UNIVERSITY OF...

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