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Direct and Indirect Optical Band Gap

  1. Dec 12, 2012 #1
    I've been looking on journals and textbook, as well as internet. Does anybody know if there is an equation to find out the value of direct optical band gap and indirect optical band gap? What is the difference of optical band gap, direct optical bandgap and indirect optical bandgap?

    also

    Does anybody recognised this equation

    Eg=hω/λae

    where Eg= optical band gap , λae= wavelength at absorption edge

    Please enlighten me.

    Thanks.
     
  2. jcsd
  3. Dec 12, 2012 #2

    DrDu

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    This question is more apt for the atomic, solid state and computational physics forum.
     
  4. Dec 12, 2012 #3
    this is reminiscent of direct bandgap vs indirect bandgap semiconductors ...

    The energy bands are plotted in momentum-space and look like wavy lines
    Good explanation and examples are shown here

    http://www.doitpoms.ac.uk/tlplib/semiconductors/direct.php

    Silicon is an indirect band gap semiconductor with a 1.1 eV bandgap width; it is too narrow to emit in the visible and also indirect, which requires a also phonon if an infrared photon is to be emitted.
     
  5. Dec 12, 2012 #4

    ZapperZ

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    Thread has been moved.

    Zz.
     
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