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Band gap energy comparison

  1. Sep 3, 2013 #1

    Which of ZnS and CdSe will have the larger band gap energy, explain.

    The answer is given as Zinc sulfide will have a larger band gap energy than cadmium selenide. Both
    are II-VI compounds, and Zn and S are both higher vertically in the periodic table than Cd and Se. In moving from bottom to top up the periodic table, band gap energy increases.

    I don't understand why moving from bottom up in the periodic table increases bang gap energy. Is it because electronegativity increases?

    Would really appreciate if anyone could explain this!

    Thank you v much in advance.
  2. jcsd
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