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Unformatted text preview: EEE 165 CSUS Instructor: Russ Tatro Chapter 3 Semiconductor Science and Light Emitting Diodes S.O. Kasap, Optoelectronics and Photonics, Principles and Practices , 2001 Solutions to Chapter 3 Homework. Problems 7, 10, 11 7 ext = 0.03125 = 3.125% 10 a) overall = 0.18% b) part (i) overall = 0.0307% and part (ii) overall = 0.0045% 11 int = 66.7% Poptical(internal) = 97 mW 3.7 External conversion efficiency The external power or conversion efficiency ext is defined as ext = Optical power output Electrical power input = P o IV One of the major factors reducing the external power efficiency is the loss of photons in extracting the emitted photons which suffer reabsorption in the pn junction materials, absorption outside the semiconductors and various reflections at interfaces. The total light output power from a particular AlGaAs red LED is 2.5 mW when the current is 50 mA and the voltage is 1.6 V. Calculate its external conversion efficiency....
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- Spring '11