Unambiguous observation of the 2s state of the light- and heavy-hole excitons in GaAs-(AlGa) As multiple-quantum-well structures

Discrete peaks are seen in the photoluminescence excitation spectra of GaAs-(AlGa)As multiple-quantum-well samples which we identify as the excited $2s$ state of the $n=1$ heavy- and light-hole excitons. The 1s-2s splitting of the excitons is accurately determined and combined with calculations of the $2s$ heavy-hole exciton binding energy to give an accurate determination of the binding energy of the ground state.