Ca Silicide Films on Si(1 0 0) and Si(1 1 1) Substrates: Structure, Optical and Electrical Properties

The crystal structure, optical and electrical properties of Ca silicide films grown by MBE and RDE processes on Si(1 0 0) and Si(1 1 1) substrates have been compared. Optical spectroscopy studies, including Raman spectroscopy, have shown two silicide phases: CaSi2 and CaSi. The RDE-grown film on Si(1 1 1) substrate with the CaSi2 phase is characterized by higher transparency than MBE-grown films. Therefore, the CaSi2 RDE-grown phase is found to be predominant and has a lower absorption in the IR region of the spectrum. After 1.5-year storage of Ca silicide film oxidation, partial destruction of the CaSi2 phase and conservation of the CaSi layer were revealed by TEM and HRTEM analyses. The complex behavior of magnetoresistance versus magnetic induction, including positive and negative curves, has been found for the MBE-grown films in the temperature range of 1.3-300 K. The RDE-grown CaSi2 film has displayed a semiconducting type of the magnetoresistance.