ASPECTS OF LOW HETEROSTRUCTURE SYMMETRY IN (311)A (IN,GA)AS GAAS/

We investigate the structural and optical properties of (In,Ga)As/GaAs heterostructures induced by the low symmetry of the [311]A orientatio n. High-resolution X-ray diffraction (HRDXD) measurements reveal the e xistence of a shear-strained unit cell. The onset of relaxation in hea vily strained structures leads to pronounced anisotropies and to satel lite splittings in the X-ray diffraction patterns. Optical investigati ons indicate that the impact of the piezoelectric fields on the ground state energy is compensated for by In segregation. Nevertheless these fields cause a pronounced reduction of the excitonic binding energy i n the (311)A structures.