Barrier-width dependence of optical transitions involving unconfined energy states in GaAs-AlxGa

Above-barrier states in GaAs–AlGaAs superlattices studied by photoconductivity and photoreflectance

“…Recently, the existence of above-barrier quasibound states have been observed in semiconductor heterostructures. The energy states confined above the barriers of periodic potentials for the electrons and holes have been investigated by different experimental methods, such as Raman spectroscopy, 1 photoluminescence excitation spectroscopy ͑PLE͒, 2 absorption spectroscopy, [2][3][4] photoreflectance spectroscopy ͑PR͒, 5,6 and piezoreflectance spectroscopy ͑PzR͒. 7 However, most previous studies were performed at very low temperature, and a clear verification of the barrier-width dependence of the transition energies has not been reported.…”

Direct observation of above-quantum-step quasibound states inGaAs/AlxLü1, Mu2, Liu3 et al. 1998Phys. Rev. B32090View full textAdd to dashboardCite

“…In recent years, however, people have investigated quasibound states in a series of semiconductor heteorostructures including quantum wells with asymmetric barriers, 1 the quasibound states in type-I superlattices, 2 heterostructures with Bragg reflection characteristics, 3 the quasibound state in a single quantum barrier, 4 the unconfined state in a superlattice, 5 the resonant transition in heterostructures, 6 etc. These quasibound states are often located at areas outside quantum wells, with their energies above potential barriers.…”

Above-barrier states inInxGa1−xAs/Worren1, Ozanyan2, Hunderi3 et al. 1998Phys. Rev. B10050View full textAdd to dashboardCite

“…2 and 7-10. It has been shown that the intensity of the transition between the first unconfined conduction-and valence-band states depends on the barrier width 4 and that the unconfined states shift to lower energies as the barrier width increases. 6,10,12,13 Recently Wen et al 14 presented a theory for above-barrier excitons in semiconductor SL's, accounting for the valenceband mixing, excitonic effects, and Fano resonances.…”