Large valence band offset in strained-layer In sub x Ga sub (1-x) As-GaAs quantum wells.

We report a determination of band offsets in strained-layer In sub x Ga sub (1-x) As-GaAs quantum wells lattice-matched to GaAs. Using a light scattering method, we find a large offset for the averaged valence bands, which extrapolates to DELTAE sub (v,av) = 0.49 eV for the InAs-GaAs system. This value contradicts previous experimental determinations but agrees with predictions of theories that consider charge transfer effects at the interface. It follows from these theories that DELTAE sub (v,av) has a surprisingly strong uniaxial strain dependence, a fact that is consistent with our experimental result. Our light scattering experiment leads to a new band structure for the In sub x Ga sub (1-x) As-GaAs system lattice matched to GaAs in which the ground state for light holes is localized in the In sub x Ga sub (1-x) As layers. This conclusion is supported by photoluminescence excitation experiments.