RAMAN-SCATTERING IN INXGA1-XAS GAAS SUPERLATTICES GROWN BY MOLECULAR-BEAM EPITAXY/

The pseudomorphic InxGa1-xAs/GaAs structures are of particular interes t because of the high value of the InxGa1-xAs electron mobility and th e great conduction band offset leading to good electron confinement at the interface. Raman scattering experiments were carried out to measu re the optical lattice modes of a series of InxGa1-xAs/GaAs strained-l ayer superlattices grown by molecular beam epitaxy on the (001) surfac e of GaAs substrates. The frequency shifts between strained and strain -free layers give a quantitative determination of strain in each type of layer. For this purpose, we measured the Raman phonon frequencies o f bulk InxGa1-xAs alloy samples for a large range of composition. Doub le-crystal X-ray rocking curve (XRC) data for superlattices are compar ed with those of Raman experiments. This allows a more valid estimatio n of the obtained results.