Ordering in GaxIn1-xAsyP1-y grown on GaAs by metalorganic vapour-phase epitaxy

We have investigated ordering behaviour in MOVPE-grown GaInAsP lattice-matc hed to GaAs using luminescence and diffraction methods. Our observations in dicate that the occurrence of ordering variants depends not only on the gro wth conditions and the layer composition but is also extremely sensitive to very small substrate misorientation from (0 0 1). For GaInAsP alloys with low arsenic content (y similar to 0.15) the ordering behaviour is very simi lar to that in the well-studied (In,Ga)P system. Polarization dependent PL reveals that in comparison to InGaP, the degree of ordering in the quaterna ry gets weaker with rising arsenic content. For higher arsenic content (y g reater than or equal to 0.5) weak ordering is detected only for layers with y approximate to 0.7 when grown with a high V/III ratio in the gas phase. The observed valence-band splittings were approximate to 12 meV for y = 0.1 5 and 8 meV for y = 0.7, respectively. (C) 1998 Elsevier Science B.V. All r ights reserved.