Long-lived excitons in InAs quantum wells under uniaxial stress

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Abstract
Exciton states of InAs quantum wells under uniaxial stress are studied with a multiband effective-mass theory. For InAs quantum wells with compressive uniaxial stress, the first valence subband can have a maximum at k≠0 several meV above the zone-center energy. When the indirect valence-band maximum is high enough to offset the difference in binding energies between the direct and indirect excitons, the formation of long-lived indirect excitons becomes both energetically and radiatively favorable. The lifetimes of the indirect excitons are found to be 3 to 5 orders of magnitude longer than those of the direct excitons.