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Negatively Charged Excitons and Photoluminescence in Asymmetric Quantum Well

Izabela Szlufarska·Arkadiusz Wojs·John J. Quinn
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Abstract

We study photoluminescence (PL) of charged excitons ($X^-$) in narrow asymmetric quantum wells in high magnetic fields B. The binding of all $X^-$ states strongly depends on the separation $δ$ of electron and hole layers. The most sensitive is the ``bright'' singlet, whose binding energy decreases quickly with increasing $δ$ even at relatively small B. As a result, the value of B at which the singlet--triplet crossing occurs in the $X^-$ spectrum also depends on $δ$ and decreases from 35 T in a symmetric 10 nm GaAs well to 16 T for $δ=0.5$ nm. Since the critical values of $δ$ at which different $X^-$ states unbind are surprisingly small compared to the well width, the observation of strongly bound $X^-$ states in an experimental PL spectrum implies virtually no layer displacement in the sample. This casts doubt on the interpretation of PL spectra of heterojunctions in terms of $X^-$ recombination.

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Izabela Szlufarska, Arkadiusz Wojs, John J. Quinn. 2000-09-17. Negatively Charged Excitons and Photoluminescence in Asymmetric Quantum Well. https://doi.org/10.1103/physrevb.63.085305

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