Electronic structure and optical properties of Ca2Si films grown on silicon different oriented substrates and calculated from first principles

The work considered the growth, optical properties and emerging interband tran-sitions in Ca2Si films grown on silicon substrates with (111), (001), and (110) orientations at two temperatures (250 degrees C and 300 degrees C) using the sacrificial-template method. The optimum temperature for MBE single-phase growth of Ca2Si is 250 degrees C. Calculations of optical func-tions from the transmission and reflection spectra were carried out within the framework of a two-layer model and by the Kramers-Kronig method. It is shown that the main peaks in the experimental reflection spectra and the optical conductivity calculated according to Kramers- Kronig are in good agreement with each other. Comparison of ab initio calculations of the en-ergy band structure and optical properties of a Ca2Si single crystal and two-dimensional Ca2Si layers with experimental data in the region of high-energy transitions showed good coincidence.