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Neutral and charged exitons (trions)

  1. Jul 29, 2015 #1
    How can we distinguish between neutral and charged exitons?
     
  2. jcsd
  3. Jul 29, 2015 #2

    fzero

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    A neutral exiton is formed from an electron and a hole, so it must have integer spin. A charged exiton would be formed from an odd number of electrons and holes, so it would have half-integer spin and corresponding magnetic moment. So the energy levels for spin up vs spin down would be split in an external magnetic field.
     
  4. Jul 29, 2015 #3
    Thank you for clarification. Another question - how can we distinguish between positively and negatively charged exitons?
     
  5. Jul 29, 2015 #4

    fzero

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    I'm not too familiar with the details in this area, but I did a quick search through some articles. Identification of the charged exiton as ##X^\pm## seems to correlate entirely with whether the material is p or n-type, which you might expect since formation of, say, ##X^-## would require a large density of electrons. I don't believe the state of the art exists to allow for direct measurement of the charge, such as by studying transport properties in an applied electric field. I found http://arxiv.org/abs/1211.0072 to be quite interesting in that they used a gate voltage to change their material from p-type to n-type and could control the formation of ##X^+## or ##X^-##. You might be able to learn more by consulting some of the classic papers in the field that are cited in that paper.
     
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