Anomalously high yields of elastically scattered12C-ions from Zr, Hf, Tl, and Hg atoms implanted into silicon

Abstract

Silicon single crystals were implanted under various conditions with Zr, Hf, Tl, and Hg. The yield of scattered 1.8 MeV ¹²C-ions was studied as a function of the angle of incidence. Around the (111) direction the normal channeling dip was observed. Around the (110) direction either a narrow peak or a narrow peak superimposed on a channeling dip was found. The occurence of the peak is interpreted as being caused by scattering from impurity atoms located in the tetrahedral interstitial holes in the silicon lattice. For a beam entering along a (111) direction these atoms are screened, but they are fully exposed to a beam entering parallel to a (110) direction. The implications of this effect to earlier measurements of the lattice location of impurity atoms in silicon and germanium will be discussed. A similar effect has recently been observed at the University of Aarhus.⁽⁶⁾