Valence band offset of GaAs/GaAs0.68P0.32 multiple quantum wells

Low-temperature photoluminescence measurements have been performed under hydrostatic pressure on GaAs/GaAs0.68P0.32 strained multiple quantum well samples grown by gas-source molecular beam epitaxy. The pressure induced crossover of the first confined electron state in the GaAs wells against the conduction band (001) X minima in the GaAs0.68P0.32 barriers has been observed, which allows a direct spectroscopic determination of the valence band offset for the heterostructure. As the result we obtain the unstrained valence band offset as 0.09±0.02 eV, which corresponds to an approximate 77:23 distribution of the energy gap difference in the conduction and valence bands, respectively, for the GaAs/GaAs0.68P0.32 system.