| The defect structure of rare-earth doped InP and $rm Insb{1-x}Gasb{x}P$ was investigated. The rare-earth impurities examined in this study were erbium, ytterbium, neodymium, thulium, and europium. Atmospheric pressure metalorganic vapor phase epitaxy was used to prepare the rare-earth doped $rm Insb{1-x}Gasb{x}P$ layers with alloy compositions ranging from x = 0 to 1. The beta-diketonate compounds of the rare-earths were used as the dopant source precursors. The rare-earth doped $rm Insb{1-x}Gasb{x}P$ alloys were characterized using Hall effect measurements, photoluminescence, and photoluminescence excitation spectroscopies.;Hall effect measurements on deliberately doped material indicated that the rare-earth impurities were electrically inactive and behaved as isoelectronic centers.;Strong characteristic optical intra-4f-shell transitions were observed upon optical pumping from Er$sp{3+}$, Nd$sp{3+}$, and Tm$sp{3+}$ at 0.801 eV, 1.119 eV, and 1.010 eV, respectively, and whose energy was independent of the alloy composition. The Yb$sp{3+}$-related intracenter luminescence, however, depended on the alloy composition ranging from 1.230 eV for x = 0 to 1.247 eV for x = 0.98. The intensity of the characteristic emission was dependent on alloy composition. The quenching of Nd$sp{3+}$, Tm$sp{3+}$, and Eu$sp{3+}$ related emission for alloy compositions less than x = 0.27, 0.38, and 1, respectively, was observed, and is explained in terms of a resonance of the respective rare-earth related trapping center with the conduction (valence) band of the host semiconductor.;The thermal quenching of the rare-earth related luminescence depended strongly on alloy composition. From the temperature dependence of the luminescence quenching, the energy levels of the isovalent trapping centers of the rare-earth impurities in the alloys were determined, and are explained in terms of a vacuum referred binding energy model. The thermal quenching data indicates that the Er, Yb, Nd, and Tm related trapping centers are located at approximately 4.43 eV, 5.62 eV, 5.73 eV, and 5.75 eV below the vacuum level, respectively.;Photoluminescence excitation spectroscopy measurements were used to study the excitation mechanisms for the characteristic rare-earth emission. A model based on the capture of excitons by the isovalent centers was proposed and found to be in good agreement with the experimental results. |
