Reflectivity Spectra of CdTe Implanted at Room and Liquid Nitrogen Temperature

The fundamental reflectivity spectra of monocrystalline CdTe, implanted with Ag ions at room temperature and with Er ions at liquid nitrogen temperature, are investigated in the 0.5-6.0 eV energy range. The analysis of the obtained spectra leads to the suggestion that temperature of implantation influences the obtained results much more decisively than values of other parameters. For the implantation carried out at 300 K no significant changes in reflectivity spectra are observed regardless of magnitude of the ion dose (up to 5 × 10$\text{}^{15}$/cm$\text{}^{2}$) and this fact, in our opinion, is due to the self-annealing effect. For samples implanted at temperature 77 K with comparable doses of ions, however, the characteristic changes of shape and intensity of reflection coefficient spectra appear. The manner of this changes gives evidence that temperature 77 K is low enough to make the radiation induced lattice defects stable (frozen-in) which are responsible for the observed behaviour of CdTe fundamental reflectivity spectra

An Analysis of Zn and Se K Edge XANES Spectra for ZnMeSe (Me = Ni, Cr, V and Ti)

Experimental studies of X-ray Absorption Near Edge Structure (XANES) have been carried out for Se and Zn K edges in ZnNiSe, ZnCrSe, ZnVSe and ZnTiSe. A comparison is made between the experimental results for a zincblende crystalline ZnMeSe (where Mc = Ni, Cr, V, and Ti) with theoretical LMTO calculations of the electron densities of states (DOS) in the conduction band for the ordered ferromagnetic phase of ZnMeSe (with 25% Me content). The agreement between the theoretical x-ray absorption edges and experimental details is not so satisfactory as for ZnMnSe and ZnFeSe, which have been obtained earlier [P.M.Lee at al., J.Phys. Condensed Matter, 6, (1994), 5771], particularly in the intensities and the energy positions of the fine structure of the XANES experimental and theoretical spectra. However, the p-like DOS for ZnMeSe around Se and Zn ions in an energy range close to the Fermi level have been compared with success. From experimental Se and Zn K edges, hybridized contributions of the transition metals in ZnNiSe, ZnCrSe, ZnVSe and ZnTiSe have been extracted and analyzed. The comparison between ternary compounds ZnNiSe, ZnCrSe and ZnVSe and pure ZnSe, taken as standard compounds, presents a characteristic maxima of p-like contribution localized at 0.25, 1.8 and 0.25 eV below ZnSe conduction band minimum (CBM), respectively. A close correlation between theoretical p-like DOS maximum in 0 - 2 eV energy range and features subtracted from experimental data is found. The contribution of Ti in ZnSe is not observed, probably due to small solubility of Ti in ZnSe (less 1%)

XANES Analysis of L3,2 Edges of Zinc Selenides with Transition Metals

X-ray Absorption Near Edge Structure (XANES) for ternary compounds Zn1-xTMxSe (TM=Cr, Mn, Fe, Co, and Ni) with different concentration x of transition metals (TM) has been studied with the use of synchrotron radiation. XANES measurements were carried out in the fluorescence detection mode using synchrotron radiation from the HE-PGM2 plane grating monochromator at BESSY. The L3.2 edges for Se, Zn and different transition metals (Cr, Mn, Fe, Co, and Ni) in Zn1-xTMxSe compounds have been analyzed. Moreover, the analysis of L3.2 edges for different transition metals in binary TMSe has also been made. The characteristic feature of L3.2 edges for transition metals containing two white lines was observed. The energy positions of these maxima are in good agreement with the theoretical results. The studies of L3.2 edges of Se in ternary compounds in comparison to the same edge of host crystal (ZnSe) allowed us to obtain information about the influence of additional 3d-states of TM on the density of states of ternary compounds