GaInPSb bulk and superlattice layers have been grown by metal organic vapour phase epitaxy (MOVPE) at low growth temperatures oil exact and misorientated InP Substrates. Optical and structural studies of the properties of the material reveal that phase separation plays an important role in the growth of this alloy. which is indicated by very broad linewidths in low-temperature photolurninescence (PL) measurements. To explain this behaviour simple miscibility gap calculations for the materials GaInPSb, GaInAsSb and GaInAsP have been performed using the regular solution model. A comparative growth analysis of GaInAsP, GaInPSb bull and InPSb, GaInAsSb and GaAsSb superlattice structures showed that just the phosphorus- and antimony-containing alloys exhibited the broad low temperature (4 K) PL linewidths (FWHM) of about 50-100 meV. So it can be assumed that due to the large difference in binding energies phosphorus-containing antimonides require much more effort for good crystal quality than equal arsenical alloys. (C) 2008 Elsevier B.V. All rights reserved.