Negatively Charged Excitons and Photoluminescence in Asymmetric Quantum Well

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 $\delta$ of electron and hole layers. The most sensitive is the ``bright'' singlet, whose binding energy decreases quickly with increasing $\delta$ 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 $\delta$ and decreases from 35 T in a symmetric 10 nm GaAs well to 16 T for $\delta =0.5$ nm. Since the critical values of $\delta$ 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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Cited by in corpus (2)

• Charged exctions in the fractional quantum Hall regime
• Resonant Enhancement of Inelastic Light Scattering in the Fractional Quantum Hall Regime at $\nu =1/3$