SURFACE STACKING-FAULTS IN CLOSE-PACKED TRANSITION-METALS

The deposition of a metallic monolayer on a close-packed surface of FCC and HCP metals can induce a surface stacking fault. The energy of such stacking faults on FCC (111) and HCP (0001) surfaces of transition metals is evaluated at 0 K with a tight-binding scheme using a continued fraction technique. Perturbative potentials near the surface are calculated using a zero charge approximation. Both homo and heteroepitaxy are considered. In the case of homoepitaxy a systematic study with the d-band filling of the substrate is carried out. It is proved that a FCC (111) surface is always in perfect registry with the substrate at 0 K. The same trend is also found for the HCP (0001) surface except for a range of d-band filling which could correspond to the elements of the IIIB column. Surface stacking fault energies are of the same order of magnitude as in the bulk. In the case of heteroepitaxy, the possibility of occurrence of surface stacking fault is discussed as a function of the d-band filling of the overlayer for a given substrate. Our conclusions are in agreement with existing experimental data.