On the isomer shifts of129I impurities implanted in semiconductors

Abstract

Mossbauer spectra of the 27.8 keV transition in129I have been measured with sources of129mTe implanted in α- and β-tin and α- and β-SiC. The spectra mainly show two single line components, just as those obtained in earlier investigations with sources of129mTe implanted in diamond, silicon and germanium. The component with isomer shift corresponding to a decreased s-electron density relative to the I− ion is attributed to the substitutionally implanted impurities, that with shift corresponding to an increased s-electron density to interstitial impurities. Plots of the shifts of both component show a linear dependence on the lattice constant for diamond, silicon and germanium and α-tin. For SiC, however, the shifts are considerably smaller than expected on the basis of this linear dependence. All shifts can be quantitatively understood on the basis of a simple model that attributes the shifts of the interstitial impurities to a compression in the host lattice and shifts of the substitutional impurities to the combined effect of compression and hybridized bonding.