Microscopic electroabsorption line shape analysis for Ga(AsSb)∕GaAs heterostructures

C. Bückers, G. Blume, A. Thränhardt, C. Schlichenmaier, P. J. Klar, G. Weiser, S. W. Koch, J. Hader, J. V. Moloney, T. J. C. Hosea, S. J. Sweeney, J.-B. Wang (+2 others)
2007 Journal of Applied Physics  
A series of Ga͑AsSb͒ / GaAs/ ͑AlGa͒As samples with varying GaAs spacer width are studied by electric-field modulated absorption ͑EA͒ and reflectance spectroscopy and modeled using a microscopic theory. The analysis of the Franz-Keldysh oscillations of GaAs capping layer and of the quantum-confined Stark shift of the lowest quantum well ͑QW͒ transitions shows the strong inhomogeneity of the built-in electric field indicating that the field modulation due to an external bias voltage differs
more » ... ltage differs significantly for the various regions of the structures. The calculations demonstrate that the line shape of the EA spectra of these samples is extremely sensitive to the value of the small conduction band offset between GaAs and Ga͑AsSb͒ as well as to the magnitude of the internal electric field changes caused by the external voltage modulation in the QW region. The EA spectra of the entire series of samples are modeled by the microscopic theory. The good agreement between experiment and theory allows us to extract the strength of the modulation of the built-in electric field in the QW region and to show that the band alignment between GaAs and Ga͑AsSb͒ is of type II with a conduction band offset of approximately 40 meV.
doi:10.1063/1.2433715 fatcat:gmdorh5dw5e37fawelb7k2lmw4