Reappraisal of the band-edge discontinuities at theAlxGa1−xAs-GaAs heterojunction

Low-temperature photoluminescence excitation spectra from ${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As-GaAs multiple quantum wells are reported. The assignment of one of the spectral features to an exciton transition involving an n=1 electron and n=3 heavy hole is not predicted by assuming the band-offset ratio to be 75:25 and a heavy-hole mass of 0.4$m_0$. Using a value of 0.34$m_0$ for this mass yields an offset ratio of 65:35 and predicts the energetic position of the $E_{13h}$ transition.