Interband transitions from the photoreflectance of GaSb/AlSb multiple quantum wells

We have measured the photoreflectance spectra at 77K of two GaSb/AlSb multiple quantum wells. Excellent quantitative agreement has been obtained between the experimental data and a theoretical calculation of inter-subband energies at Λ (GaSb). This agreement extends over the entire energy range where the hole states are confined and the electron states are below the X conduction band minimum of AlSb. This has made it possible to determine a conduction band offset parameter of 0.85 ± 0.08 (before strain) and the strain distribution. Deviations from the agreement beyond this energy range provide evidence for the mixing of the Λ-X states.