PROPERTIES OF MBE GROWN CDYBTE AND ZNYBTE ON GAAS(100) SUBSTRATES

ZnYbTe and CdYbTe thin films were grown by molecular beam epitaxy (MBE ) on ZnTe and CdTe buffer layers crystallized on GaAs(100) substrates. At the chosen growth temperature (320 degrees C for CdYbTe and 340 de grees C for ZnYbTe) the maximum concentration of ytterbium was found t o be 5% in CdTe and 3% in ZnTe. The layers were characterized by X-ray diffraction, photoluminescence (PL) and reflectivity measurements. X- ray investigations have shown that there was a small admixture of pure YbTe in the samples. From the optical measurements it follows that in CdYbTe and ZnYbTe, Yb can be found both in 2(+) (as in YbTe) and 3(+) (as in Yb doped II-VI compounds) valence state. The relatively broad PL spectra detected at the energies close to the Yb3+ 4f(13)(2F(5/2) - -> F-2(7/2)) transitions indicate that at such a high concentration Yb incorporates with certain inhomogeneity into the crystal lattices of ZnTe and CdTe.