CONDENSED MATTER PHYSICS 171.405 / 171.621 Instructor: N.P. Armitage Grader: Paula Mellado Fall 2007 Problem Set # 3 Due to Grader’s mail box by Nov. 2nd ============================= Q #1: Kittel Problem 8.1 ============================= Q #2: Kittel Problem 8.2 ============================= Q #3: The effective mass of electrons at the lower conduction band edge of a semiconductor is three times higher than that of holes at the upper valence band edge. How far is the Fermi energy E_F located from the middle of the forbidden band in the case of intrinsic conduction? The band gap energy E_g must exceed 8 k_b T; why is this a prerequisite for the calculation? ============================= Q #4: Explain the operation of a solar cell in which a p-n junction is illuminated. Assume a closed circuit containing an external resistance R. Make qualitative sketches of the current-voltage relationships with and without incident light. What is the minimum frequency which the light must have? What is the theoretical efficiency of as a function of the frequency
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This note was uploaded on 12/06/2009 for the course PHYSICS 171.405 taught by Professor N.peterarmitage during the Fall '07 term at Johns Hopkins.