Biexcitons in ZnSe Quantum Wells
The quasi-2-dimensional character of electron and hole wavefunctions in a semiconductor quantum well leads to an enhancement of the exciton binding energy and oscillator strength. This effect has been justified theoretically and well confirmed experimentally by many authors in the case of GaAs quantum wells . For similar reasons, the forced confinement of carriers with opposite charge in the same ultrathin layer is expected to increase the biexciton stability. A calculation by Kleiman  predicts that in the best case, the biexciton binding energy can exceed half the Rydberg (see Fig. 1). However, on experimental side, there is so far very little evidence  for biexcitons in quantum wells in general and GaAs quantum wells in particular despite the considerable amount of spectroscopy studies performed in this type of material. This probably reflects the fact that the binding energy of the biexciton in bulk GaAs is very small to start with, so that it remains small on an absolute scale even after confinement enhancement.
KeywordsExcitation Spectrum Exciton Binding Energy Free Exciton Forced Confinement Biexciton Binding Energy
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- For a recent review see: Semiconductors and Semimetals, 24 Academic Press, ed. R. DingleGoogle Scholar
- For a review of ZnSe quantum well properties see for instance A.V. NurmikkoGoogle Scholar
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