SCANNING PHOTOLUMINESCENCE CHARACTERIZATION OF IRON-DOPED GAS-SOURCE MOLECULAR-BEAM EPITAXY INDIUM-PHOSPHIDE LAYERS

Iron-doped indium phosphide layers were grown by gas source molecular beam epitaxy with a high purity solid iron source. The iron concentrat ion 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-insul ating or n+. Some iron-doped layers were also produced directly on a s emi-insulating substrate. Resistivity values of 10(3) OMEGA CM to 10(8 ) OMEGA cm were obtained, depending on the iron concentration. The iro n incorporation was found to be related to the growth conditions, espe cially 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 latte r technique used either photoluminescence integrated signal measuremen ts 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 concentratio ns of a few 10(17) cm-3, the photoluminescence intensity was comparabl e with that obtained for bulk semi-insulating substrates, and the dens ity of defects was found to be (2-5) x 10(4) CM-2.