Third International Conference on Optics of Excitons in Confined

Le Journal de Physique IV 03 (1993) C5-295-C5-298
DOI: 10.1051/jp4:1993559

Indium segregation and misorientation effects on the optical properties of MBE grown In_0.35Ga_0.65As/GaAs quantum wells

C. MONIER¹, J. LEYMARIE¹, A. MARTI CESHIN², N. GRANDJEAN², A. VASSON¹, A.-M. VASSON¹, M. LEROUX² and J. MASSIES<sup>2

1</sup>  Laboratoire de Physique des Milieux Condensés, Unité de Recherche Associée au Centre National de la Recherche Scientifique 796, Université Blaise Pascal Clermont II, 24 avenue des Landais, 63177 Aubière cedex, France
²  Laboratoire de Physique du Solide et Enegie Solaire, Centre National de la Recherche Scientifique, rue Bernard Grégory, 06560 Valbonne, France

Abstract
Photoluminescence (PL), reflectivity and thermally-detected optical absorption (TDOA) experiments have been carried out, at liquid helium temperatures, on In_0.35Ga_0.65As/GaAs quantum wells (QWs) with different thicknesses of 4, 6, 8 and 10 monolayers (MLs), grown by molecular beam epitaxy (MBE) on substrates oriented exactly on (100) (nominal growth) or misoriented by 4° or 6° towards (11l)_Ga (vicinal growth). Indium segregation effects are considered in the comparison of the calculated fundamental (e₁hh₁) transition energies of the QWs with the experimental results. Within the framework of a simple model, a segregation energy of 0.35 eV is used to fit the experimental data. It is shown that the misorientation improves the optical properties of QWs: diminution of the spectral broadenings and reduction of the blue shift between reflectivity structures or TDOA peaks and luminescence lines. This suggests a better quality of the interfaces and an improvement of the strain homogeneity. A step edge effect on the fundamental transition energy of the 6 and 8 ML quantum wells is shown but the blue shift observed for a growth on a 4° off misoriented surface can also be due to a modification of the growth mode.

© EDP Sciences 1993