Binding of Quasi-Two-Dimensional Biexcitons

Abstract

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Biexcitonic molecules survive excitons at the Mott transition

“…Moreover, when the carrier density in the QW increases, the excitonic resonance seems to disappear at lower injection than does the biexcitonic one. This observation is contrasting with the intuitive expectation exposed above: highdensity effects are supposed to first screen the biexciton resonance, owing to its larger Bohr radius and smaller binding energy 14,17 .…”

“…The latter is evidenced by the saturation of the PL intensity amplitude at high densities and a characteristic asymmetric emission lineshape, which can be accurately modelled using Fermi's golden rule. Similarly to experiments conducted in GaAs-based QWs, the MT appears to be smooth 17 . However, contrary to the GaAs system, here the e-h plasma builds up from the biexciton state rather than from the exciton resonance.…”

“…The biexciton-binding energy is estimated from the CW PL spectra under moderate injection to be B8 meV. Hence, the ratio of the biexciton-to exciton-binding energy is B0.26, that is, a value close to the 0.228 expected for weakly disordered structures 17,18 .…”

Influence of well-width fluctuations on the binding energy of excitons, charged excitons, and biexcitons inGaAs-based quantum wells

“…These systems show nontrivial Coulomb correlation effects leading to interesting optical and transport characteristics not seen in bulk materials. A strong increase of the binding energy of the excitonic complexes was found experimentally [1,2,3,4,5,6,7,8,9,10] with decreasing quantum well (QW) width and increasing magnetic field [11].…”

Mixed biexcitons in single quantum wells

“…[4][5][6][7] So far, these studies consider mainly the biexciton formation from two heavy-hole excitons (X h ). Biexcitons involving light-hole excitons (X l ) have been observed, 8 but no distinction between mixed and pure lighthole biexcitons has been made.…”