Properties of MBE grown CdYbTe and ZnYbTe on GaAs(100) substrates

Abstract

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°C for CdYbTe and 340°C for ZnYbTe) the maximum concentration of ytterbium was found to 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+4f13(2F52 → 2F72) transitions indicate that at such a high concentration Yb incorporates with certain inhomogeneity into the crystal lattices of ZnTe and CdTe.