Anatolii N Oraevsky

Microphotoluminscence of C60 fullerenes doped with ions of rare-earth elements

Optical properties of various fullerene matrices based on C60 were studied by scanning microphotoluminescence in the range of 660–2300 nm. Variations observed in the photoluminescence spectra at room temperature after prolonged exposure to focused He−Ne laser irradiation directly after implantation of ions of rare-earth elements (Yb+ Nd+, or Er+) or after an isochronal thermal annealing of ion-implanted samples in the temperature range of 50–150°C are attributed to changes in the ratio of the generation and recombination rates of native lattice defects. Photoluminescence of fullerene matrices implanted with Yb+ ions has an intracenter origin at liquid-nitrogen temperature. A variation in the photoluminescence of fullerene matrices following dissolution of the samples in toluene and subsequent recrystallization indicates that Yb atoms are involved in the formation of fullerene-based endohedral or more intricate cluster complexes. The results obtained make it possible to identify a number of technological factors that are important for the production of new photoluminescent media, including those for laser operation.

Influence of Defects and Transition Elements in Substrates Of Semi-Insulating Gaas on Optical Properties of Algaas/Gaas Quantum-Well Structures

The influence of transition elements on uniformity of optical properties of semi-insulating GaAs and Al-GaAs/GaAs quantum-well structures grown by molecular-beam epitaxy was studied by scanning micropho-toluminescence (MPL) and optical absorption. It is ascertained that the gettering properties of Ti, V, and Cr atoms suppress agglomeration of lattice defects and background impurities in the vicinity of disloca-tions. It is demonstrated that, in the quantum-well (QW) structures doped with Ti, the dependence of MPL intensity on the excitation level is nonlinear (bistable).