Supersoft silicides: Ab initio study of (001) TSi surfaces and (001) Si/TSi (T=Fe, Co, and Ni) interfaces

摘要

The aim of our ab initio study for metastable TSi compounds (T=Fe,Co,Ni) with B2 structure is to investigate the possibility of epitaxial growth of the supersoft silicides, CoSi and NiSi, on a Si substrate. For the free TSi(001) surfaces we present data for the energetics as well as for electronic, structural, and magnetic properties. From the analysis of the surface energies, we derived that for FeSi a Si-terminated surface is most favorable. For CoSi in Co-rich conditions, Co termination, is lowest in energy, otherwise Si termination is predicted, whereas NiSi is definitely Ni terminated. Fe- and Co-terminated surfaces of FeSi and CoSi, respectively, carry magnetic moments, in contrast to NiSi. Furthermore, the energetics of TSi(001)/Si(001) interfaces was studied resulting in interface energies of 0.79, 0.66, and 0.74 eV for the FeSi-, CoSi-, and NiSi-based interfaces, respectively. These rather low interface energies clearly indicate that supersoft silicides might be successfully grown on Si by means of epitaxial techniques.