InP:Fe semi-insulating layers by chemical beam epitaxy

High resistivity InP layers were grown by chemical beam epitaxy evaporating metallic iron with the use of a conventional Knudsen cell. The structural and optical characteristics of the epilayers were analysed by secondary ion mass spectroscopy, high resolution X-ray diffraction, photoluminescence, absorption and transmission electron microscopy, Electrical measurements were performed on lithographically defined mesa diodes. Iron concentrations ranging from 7x10(15) to 4x10(19) atoms/cm(3) were investigated. Mirror-like morphologies were obtained for iron concentrations up to 7x10(18) atoms/cm(3) The peak resistivity was 1.3x10(8) Omega . cm. For dopant concentrations higher than 1x10(18) atoms/cm(3), a drop in resistivity occurred. This could be related to the formation of precipitates as confirmed by transmission electron microscopy. InGaAs/InP structures with iron-doped wells were also studied.