Light scattering determination of band offsets in GaAs-(AlGa)As quantum wells.

The conduction band offset in GaAs-Al(x)Ga(1-x)As quantum wells is determined with a new light scattering method. A value of DeltaE(C)/DeltaE(g) = Q(e) = 0.69 is found for x= 0.06. The conduction band discontinuity DeltaE(c) is obtained from electronic light scattering in photoexcited samples. The total gap discontinuity DeltaE(g) is deduced from resonance Raman scattering by (AlGa)As phonons in the same sample. The light scattering method is unique because DeltaE(c) can be determined regardless of the valence band structure or exciton binding energies. It also allows a direct measurement of DeltaE(g), so that an exact knowledge of the alloy composition in Al(x)Ga (1-x)As is no longer needed.