Scanning photoluminescence characterization of iron-doped gas source molecular beam epitaxy indium phosphide layers

Abstract Iron-doped indium phosphide layers were grown by gas source molecular beam epitaxy with a high purity solid iron source. The iron concentration varied from some 10 16 cm −3 to a few 10 19 cm −3 . N-i-n or n + -i-n + layer structures were realized on two types of substrate: semi-insulating or n + . Some iron-doped layers were also produced directly on a semi-insulating substrate. Resistivity values of 10 3 Ω cm to 10 8 Ω cm were obtained, depending on the iron concentration. The iron incorporation was found to be related to the growth conditions, especially the iron cell temperature and the growth substrate temperature. The layers were characterized by secondary ion mass spectrometry and scanning photoluminescence measurements at room temperature. The latter technique used either photoluminescence integrated signal measurements or recorded InP spectra. The photoluminescence intensity was found to be a valuable parameter for evaluating the iron incorporation. For layers having the highest resistivities, obtained at iron concentrations of a few 10 17 cm −3 , the photoluminescence intensity was comparable with that obtained for bulk semi-insulating substrates, and the density of defects was found to be (2–5) × 10 4 cm −2 .