Paramagnetic-Resonance Studies of Rare-Earth Impurities in II-VI Compounds

Abstract

An electron-paramagnetic-resonance study of rare-earth impurities in II-VI compounds has been made. Isolated trivalent rare-earth ions are found to be substitutional for the metal ion in the zinc-blende crystals. Spectra from trivalent ions both at the isolated substitutional site and incorporated in additional unknown ways are observed in the wurtzite crystals. Shifts in the $g$ factor are noted to depend on host covalency in the case of isolated substitutional ${\mathrm{Yb}}^{3+}$. ${\mathrm{Yb}}^{3+}$-${(\mathrm{noble}\mathrm{metal})}^{1+}$ associates are studied in CdTe. Observation of ligand hyperfine structure shows that, in this instance, the rare earth is interstitial. Generally, the results indicate that the point-charge model may be usefully applied to determine the mechanism of rare-earth incorporation in II-VI compounds from observation of their paramagnetic-resonance spectra.