DISTINGUISHING THE CLOSE-PACKED HEXAGONAL AND FACE-CENTERED-CUBIC PHASES OF THE METALLIZATION OF DIAMOND BY POLARIZATION-DEPENDENT EXTENDEDX-RAY-ABSORPTION FINE-STRUCTURE

Polarization-dependent extended x-ray absorption fine structure (PD-EX AFS) measurements have been made on a single-crystal 1000-Angstrom-thi ck Co film deposited on (100) diamond. By comparing the EXAFS signals corresponding to the in-plane and out-of-plane structure relative to t he film plane, we clearly determine that the film does establish the f ace centered cubic (fcc) phase. Distinguishing between the hcp and fcc phases can thus be performed by qualitatively noting the polarization dependence of the Fourier transform peak amplitudes corresponding to the third and fourth coordination shells. This EXAFS study shows that the Co film studied here is unambiguously in the fcc phase. The Fourie r transform peaks corresponding to the first nearest neighbors, parall el and perpendicular to the film, have been compared. Results indicate less than a 0.0075 Angstrom difference between in-plane and out-of-pl ane bondlengths, no significant change in coordination number and less than a 0.001 Angstrom(2) difference in EXAFS Debye-Waller factors. Al l of these results indicate no tetragonal distortion of the fcc Co cry stal lattice. This technique should prove valuable in future studies w hen trying to determine the crystallinity of thin films. (C) 1996 Amer ican Vacuum Society.