Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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?


    Does anybody recognised this equation


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

    Please enlighten me.

  2. jcsd
  3. Dec 12, 2012 #2


    User Avatar
    Science Advisor

    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


    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


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Thread has been moved.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook