Realization and modeling of a pseudomorphic (GaAs(1-x)Sb(x)-In(y)Ga(1-y)As)/GaAs bilayer-quantum well

We have realized a (GaAs1-xSbx-InyGa1-yAs)/GaAs bilayer-quantum well (BQW), which consists of two adjacent pseudomorphic layers of GaAs1-xSbx and InyGa1-yAs sandwiched between GaAs barriers. Photoluminescence was observed at longer wavelengths than those found for corresponding InyGa1-yAs/GaAs and GaAs1-xSbx/GaAs single quantum wells (SQW), which indicates a type-II band alignment in the BQW. The longest 300 K emission wavelength achieved so far was 1.332 mu m. For an accurate determination of the band offset between GaAs1-xSbx and GaAs, required for a theoretical modeling of the interband transition energies of these BQWs, a large set of GaAs1-xSbx/GaAs SQWs was prepared from which a type-II band alignment was deduced, with the valence band discontinuity ratio Qupsilon found to depend on the Sb concentration x (Qupsilon =1.76+1.34 x). With this parameter it was possible to calculate the expected interband transition energies in a BQW structure without any adjustable parameters. The ca lculations are in agreement with experimental data within a range of +or-4%.