Abstract
Measurement of the stacking faults (SFs) formed in a pseudo-hexagonal closed packed (pseudo-hcp) film is proposed using laboratory-scale X-ray diffractometer. The pseudo-hcp structure includes (111)-oriented face centered cubic (fcc), c-plane oriented hcp, and their mediate structures with the SFs. Diffractions from (11.0) and (10.0) planes, D_H and D_L, were observed in the in-plane X-ray diffraction (XRD) profiles of the pseudo-hcp materials. The structure factor revealed that D_H and D_L originates from the number of total atomic layers and the imbalance of the number of A, B, and C atomic layers, respectively. Therefore, the intensity ratio of D_H to D_L, corrected by Lorentz-polarization and atomic scattering factors (corrected I_L/I_H), is defined as the degree of SFs for pseudo-hcp materials from the stacking probability, independent of thickness, compositional atoms, and lattice constants. Theoretical values of the corrected I_L/I_H are 0.25 for perfect hcp stacking and 0 for perfect fcc stacking, and statistical calculations revealed that this index is very sensitive to the approach of perfect hcp stacking order rather than that of perfect fcc stacking order. By applying this evaluation to experimentally sputtered thin films, it was clarified that critical number of valence electron for fcc-hcp transition was found to be "9" for a transition-metal alloy thin film. Proposed evaluation is quite useful for material and process development of perpendicular recording media.
