Crystal structure characterization of ion-beam-synthesized CoxY1-xSi1.7 silicide

Heteroepitaxial ternary CoxY1-xSi1.7 silicide (x > 0.27) has been formed by Co implantation into YSi1.7/Si(111). The formation of this compound is con firmed by an x-ray symmetric theta-2 theta scan. However, the theta-2 theta scan alone cannot discriminate between the possible phases (tetragonal, or thorhombic, or hexagonal) of this compound. On the other hand, Rutherford b ackscattering (RBS)/channeling confirms that this silicide is hexagonal and that its azimuthal orientation is CoYSi1.7[0001]//Si[111] and CoYSi1.7{$11 (2) over bar 0}//Si{110}. In addition, the lattice constants of the ternar y silicide a(epi) = 0.3989 nm (which means that the lattice mismatch is 3.9 % relative to the Si substrate! and c(epi) = 0.3982 nm have been determined by RBS/channeling and x-ray diffraction. (C) 1999 American Institute of Ph ysics. [S0021-8979(99)09709-1].