NOVELTY - An optoelectronic device is made by growing a first structure, introducing a surfactant in a molar ratio of surfactant to group-III precursor of greater than or equal to 1 x 10-5, and growing a top layer. The top layer of the device comprises an ordering parameter (eta) of less than or equal to 0.3.    USE - For making an optoelectronic device, e.g. solar cell.    ADVANTAGE - The method provides an optoelectronic device having a top sub-cell that converts photogenerated current densities at as high a voltage as possible and thus maximizes the efficiency of the photovoltaic cell. The top sub-cell has the highest possible band gap achievable for lattice-matched gallium-indium-phosphorus (GaInP).    DETAILED DESCRIPTION - Manufacture of an optoelectronic device comprises growing a first structure, introducing a surfactant in a molar ratio of surfactant to group-III precursor of greater than or equal to 1 x 10-5, and growing a top layer. The top layer of the device comprises an ordering parameter (eta;) of less than or equal to 0.3 satisfying equation (1).    INDEPENDENT CLAIMS are also included for:    (a) an optoelectronic device comprising a substrate, an isoelectronic surfactant-induced lattice disordered top layer disposed over the substrate;    (b) a solar cell having a gallium indium phosphide (GaInP) top layer, comprising a lower structure, a subsequent structure over the lower structure, where the top layer has an isoelectronic surfactant and is Ga0.505In0.495P or Ga0.515In0.485P; and    (c) a satellite system comprising a satellite and solar cells including a top layer of GaInP, GaInAs, GaPAs, GaInPAs, AlInP, AlGaInP, AlGaAs, AlGaInAs, AlGaAsSb, AlGaPAsAlInAs, InPAs, AlInPAs, SiGe, CdZnSe, CdZnTe, ZnSSe, ZnSeTe, CuGaInSe, CuGaInSSe, and AgGaInSe (where: As= arsenide; Al= aluminum; Sb= antimony; Si= silicon; Ge= germanium; Cd= cadmium; Zn= zinc; Se= selenium; Te= tellurium; S= sulfur; Cu= copper).    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a multi-junction solar cell.