Observation of Heterostructure Epitaxy of Pt-doped Ni-Monosilicide on Si(001)

Abstract: The objective of this study was to determine detailed microstructure of Ni1？xPtxSi film formed on a Si(001) substrate via a melting/quenching process using milli-second annealing. The orthorhombic Ni1？xPtxSi film was found to be able to grow with an epitaxial relationship of Ni1？xPtxSi[010]//Si[110], Ni1？xPtxSi(400)//Si(33(_)1), and Ni1？xPtxSi (104)//Si(004). According to X-ray diffraction measurements, volume expansion of the Ni1？xPtxSi film due to Pt incorporation was mainly accommodated by an increase in only one direction nearly parallel to the film surface (lattice parameter a). This was explained by minimum coherent strain at the Ni1？xPtxSi (104)/Si(004) interface with an epitaxial growth tendency. Atomic-scale scanning transmission electron microscopy analyses revealed that the interface of Ni1？xPtxSi/Si had a repetitive atomic-step feature with energetically favorable Ni1？xPtxSi(004) terraces and (400) structural ledges to increase the coherent area. By generating an array of misfit dislocations with an extra half plane of Ni1？xPtxSi(020), it further relieved the elastic strain.