Band offsets from two special GaAs-AlxGa1−xAs quantum-well structures

Half-parabolic quantum wells and two-stepped quantum wells have been grown by molecular-beam epitaxy with the GaAs-${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As system and investigated by photoluminescence techniques to determine the band offsets at the heterointerfaces. Both structures provide interband transitions that are sensitive to the partitioning of the energy-gap discontinuity Δ$E_g$=Δ$E_c$+Δ$E_v$ between the conduction and valence bands. It is concluded that the data require valence-band offsets Δ$E_v$ equal to 38% and 41% of Δ$E_g$ for the half-parabolic wells and the two-stepped wells, respectively. These band offsets are therefore in agreement with the trend of other recent determinations.