Ordering in GaInP2 studied by optical spectroscopy

The optical properties of spontaneously ordered GaInP2 grown by MOVPE are studied by means of photoluminescence, time-resolved photoluminescence, and polarization dependent photoluminescence excitation spectroscopy. Ordered samples grown on a substrate which is misoriented 6 degrees toward [111](B) show clear excitonic features both in luminescence and absorption. In excitation spectra both valence band edges an clearly resolved and are shown to be polarization dependent as predicted by band structure calculations. In these samples an additional non-excitonic low-energy photoluminescence emission is observed the peak energy of which depends strongly on excitation density and temperature and which shows extremely long luminescence lifetimes. A density of states model for ordered GaInP2 is proposed which allows to explain the results obtained in the last few years. The density of states model is discussed with respect to the microstructure of the ordered alloy as known from TEM investigations.