OPTICAL INVESTIGATION OF THE INFLUENCE OF SUBSTRATE ORIENTATION ON SPONTANEOUS ORDERING IN GA0.5IN0.5P ALLOY

The influence of substrate misorientation on the electronic structure of ordered Ga0.5In0.5P is investigated by piezomodulated reflectivity, photoluminescence and photoluminescence excitation spectroscopy. A '' U''-shaped dependence of the band gap on the misorientation angle is o bserved. In addition, we have investigated the dependence of the cryst al field and spin-orbit splitting, photoluminescence linewidth and the Stokes shift on substrate misorientation in these materials. The depe ndence of the crystal field and spin orbit splitting on the band gap o f the alloy is found to be independent of substrate misorientation and is shown to be in reasonable agreement with a theoretical model relat ing these quantities to the long range order parameter in the alloy. T he PL linewidth and Stokes shift both decrease with increasing band ga p.