alpha-FeSi(2)as a Buffer Layer for beta-FeSi(2)Growth: Analysis of Orientation Relationships in Silicide/Silicon, Silicide/Silicide Heterointerfaces

In this manuscript, we attempt to clarify the capability of utilisation of α-FeSi2 nanocrystals as a buffer layer for growth of monocrystalline/high-quality β-FeSi2 direct-gap semiconductor from the point of view of the crystal lattice misfits and near coincidence site (NCS) lattices. Iron silicides-based nanostructures have a wide spectrum of possible industrial applications in different fields. Mainly, interest in these functional materials is caused by their ecological safety and Earth’s core abundance that give us the opportunity for greener future with highly effective electronic devices. β-FeSi2 phase due to its allowed direct transition with energy close to 0.87 eV can be used as active material in light emission diodes (LED). Utilisation of buffer layers between silicon substrate and give one more tool to engineer the band structure of semiconducting β‑FeSi2 phase. We attempt to clarify the capability of the utilisation of the α-FeSi2 phase as a buffer layer for the growth of β-FeSi2 direct-gap semiconductor from the point of view of the crystal lattice misfits and near coincidence site (NCS) lattices. Possible β-FeSi2/α-,γ-,s-FeSi2/Si orientation relationships (ORs) and habit planes were examined with crystallogeometrical approaches and compared with β-FeSi2/Si ones. The lowest interplanar and interatomic spacing misfits between silicon lattice and a silicide one are observed for the pair of s-FeSi2{011}[200]/Si{022}[100] at room temperature and equal to –0.57%. The least interplanar and interatomic spacing misfit of 1.7 and 1.88%, respectively, for β-FeSi2/Si, can be decreased as low as –0.67 (interplanar) and 0.87 (interatomic) % by placing an α-FeSi2 layer between silicon and β-FeSi2 phase. It is stated that the growth of metastable γ-FeSi2 is also favourable on silicon due to low interplanar and interatomic spacing misfit (–0.77%) and a higher density of NCS in comparison with s-FeSi2. Design and technological procedure for the synthesis of possible β-FeSi2/α-FeSi2/Si heterostructure have been proposed based on the results obtained.