Interplay of localization and anisotropy in the optical properties of ordered (AlxGa1-x)0.52In0.48P

Using polarized spatially integrated photoluminescence (PL) and polarized micro-photolumincscence (mu-PL) experiments we have investigated the optical properties of ordered (Al-0.5 Ga-0.5)(0.52)In-0.48 P. The anisotropy of the PL cannot be completely understood in terms of the reduced symmetry of the CuPtB-structure. Exciton localization which arises from the inhomogeneous microstructure of ordered crystals is shown to affect the polarization of the PL significantly. Increasing the temperature from 5 to 50-100 K leads to a thermally activated occupation of deeply localized states. The polarization of the PL from these states stands in contradiction to the anisotropy which arises from the CuPtB-structure. We demonstrate this by PL measurements of the [0 0 1]-emission and by mu-PL measurements on the (1 1 0) cleaved edge. (C) 2000 Elsevier Science B.V. All rights reserved.