Iron doping of InP andGaInAsP(&lgr;g=1.05 &mgr;m)layers grown by metalorganic molecular beam epitaxy was studied using elemental source material in combination with a conventional effusion cell. This study was aimed at the creation of semi-insulating optical waveguides under growth conditions compatible with selective area growth. Secondary ion mass spectroscopy measurements revealed a reproducible and homogeneous incorporation behavior of the iron dopant in the materials investigated. Resistivities in excess of109 &OHgr; cmwere obtained for both compositions at medium doping levels. GaInAsP/InP waveguide structures grown at485 °C—the minimum temperature necessary for selective deposition—exhibited averaged resistivities of5×107 &OHgr; cmin combination with optical losses of2.5±0.5 dB/cm.©1998 American Institute of Physics.