Photoluminescence investigation of superlattice ordering in organometallicvapour phase epitaxy grown InGaP layers

InGaP alloys, lattice matched to GaAs (100), were grown in different organo metallic vapour phase epitaxy reactors operating at low pressure. cw-photol uminescence spectroscopy was used to investigate the role of growth tempera ture, substrate misorientation and doping on the ordering effect. The bleac hing of the exciton peak and a strong thermal quenching of the PL efficienc y was observed in different samples. The line-shape analysis of PL spectra obtained at different temperatures and excitation intensities confirmed the band gap dependence on the ordering effect; a maximum band gap reduction ( BGR) of similar to 109 meV was observed, corresponding to an order paramete r eta = 0.47, obtained for nominally undoped layers grown at 640 degreesC o n GaAs (100) substrates, 2 degrees misoriented toward the (110) direction. A weak dependence of such maximum on degree and direction of the substrate misorientation seems to be possible; the temperature dependence of the PL p eaks resulted the weaker the higher the ordering presence. In the case of b oth n- and p-type doped InGaP layers, the effect of doping in reducing both the ordering formation and the average size of ordered domains was confirm ed. (C) 2001 Elsevier Science B.V. All rights reserved.