Band discontinuities and calculations of GaAs-AlGaAs superlattice structures

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Abstract
The first two optical transition energies of GaAs-Ga(Al)As superlattices and multiquantum wells with small well widths are quite sensitive to the band discontinuity. On a series of samples the parameters of which are determined by x-ray diffraction, we compare the energies measured in photoluminescence and photoluminescence excitation spectroscopies with the results of calculations within the framework of the envelope function approach and with the simple Kronig–Penney model. The envelope function approximation models give transition energies systematically smaller than the experimental values and the discrepancy increases when the well width decreases. With the Kronig–Penney model, both excitonic transitions are satisfactorily calculated for each sample with a conduction-band offset around 75%, but we do not find a unique value of the conduction-band offset for all samples.