2018
Defect and Diffusion Forum, Scopus
Article
Defect and Diffusion Forum
Switzerland, Stafa-Zurich, Trans Tech Publications
Defect and Diffusion Forum Vol. 386 (2018) 3-8
1662-9507
Galkin N. G. et al. Comparison of the structural, optical and thermoelectrical properties of Ca silicide films with variable composition on Si substrates //Defect and Diffusion Forum. – Trans Tech Publications Ltd, 2018. – Т. 386. – С. 3-8.
The growth, structure, optical, electrical and thermoelectric properties of calcium silicides of various compositions on silicon substrates with (100) and (111) orientations were experimentally studied. It was found that when the atoms of Ca and Si are co-deposited on atomically clean silicon, the basis phases in the composition of the formed films depends on the substrate temperature and the annealing temperature: Ca2Si (TSi = 20°C, Tann = 330°C), CaSi (TSi = 190-320°C, Tann = 330°C) and CaSi2 (TSi = 500°C). It was established that the Ca2Si phase is a direct-gap semiconductor with a band gap of 0.82±0.02 eV, large contribution of defect levels to the absorption coefficient at energies 0.25 - 0.50 eV and huge transmission up 90% in the far IR region. In CaSi-based films the high transmission (30-40%) up to 25 μm was observed, which corresponds to a semimetal with a constant density of states near the Fermi level. It was found that CaSi-based films have the maximum Seebeck coefficient and the power factor (up to 430 μV/K and up to 1.14 × 10-6 W/(K2m), respectively) at 330K. CaSi2 films with CaSi2 lattice stretching and epitaxial ordering relative to the Si (100) substrate exhibit semimetal properties, with very high conductivity and light transparency (up 12%) in the photon energy range 0.06 - 0.65 eV.
https://doi.org/10.4028/www.scientific.net/DDF.386.3