TERRACE LENGTH COMMENSURABILITY AND SURFACE RECONSTRUCTION IN HIGHLY STRAINED INGAAS/GAAS QUANTUM-WELLS GROWN ON VICINAL SUBSTRATES

We present a study of the electronic properties of In(x)Ga1-xAs/GaAs quantum wells when grown on vicinal substrates, based on photoluminescence (PL) and PL excitation experiments under high magnetic field. The samples measured have a wide range of In contents, various misorientation angles (up to 6-degrees) and well widths. It is found that larger miscut angles produce higher quality samples i.e. the Stokes shifts are smaller and the PL peaks display lower inhomogeneous broadening. As to the luminescence and free electron-hole absorption energies, the results show an increase with miscut angle. Yet this increase is not monotonic. The observed behaviour is attributed to the terrace length commensurability with the (2x4) unit cell of the (001) GaAs reconstructed surface. Binding energy and heavy hole exciton reduced in-plane mass are hardly terrace length dependent. The results obtained are well explained by numerical calculations that take into account the strain inhomogeneity and the In segregation associated with this type of quantum wells.