α-FeSi2 as a Buffer Layer for β-FeSi2 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. [ABSTRACT FROM AUTHOR]