CONDENSED MATTER PHYSICS 171.405 / 171.621Instructor: N.P. ArmitageGrader: Paula MelladoFall 2007Problem Set # 3Due 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 of the light?
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Condensed matter physics, Kittel, valence band edge, Paula Mellado, gap energy E_g