21 oplcal pumping and populalon inversion in many

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Unformatted text preview:   o  use GaAs for example   Crystals have high n making it hard to get the light out. 18 Photo ­Diodes, Solar Cells   photon generates electron hole pair in or near the depleLon region.   holes and electrons are pushed in opposite direcLons by the E field of the juncLon.   Current flows or a voltage is built up.   keep N ­type region thin so pairs flow efficiently. 19 Clicker: Energy Bands   The development of semiconductors was based on an understanding of the band structure in solids. What is the main property of the bands found in semiconductors? A.  There is a small gap between the conducLon band and the valence band. B.  The conducLon band is half filled. C.  There is a large gap between the conducLon band and the valence band. D.  There i...
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This note was uploaded on 02/24/2014 for the course PHYS 2D taught by Professor Hirsch during the Winter '08 term at UCSD.

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