Morphology and optical properties of α-Si:Y films, obtained by electron-beam evaporation method

Abstract

This paper presents the results of AFM, Raman, IR spectroscopy and ellipsometry of α-Si:Y films prepared by electron-beam evaporation. The influence of the type and temperature of substrates, as well as the evaporation rate on film morphology, composition and optical properties are studied. The evaporation rate increase allows to enhance the growth of films on p-Si up to 0.1 μm/min. The obtained α-Si:Y films possess an amorphous structure with a small amount of nanocrystalline inclusions. The formation of nanocrystalline inclusions could be generated by SiHх, peaks of which are clearly pronounced at 650, 890 and 2125 сm⁻¹ in the IR spectrum or yttrium impurities. The ellipsometry results show that α-Si:Y films have the high absorption coefficient, refraction index is 3.4 at the wavelength λ = 620 nm. The optical bandgap drops from 2.0 to 1.17 eV when the substrate temperature increases (140 to 300 °С).