Non-doped and doped Mg stannide films on Si(111) substrates: Formation, optical, and electrical properties

Abstract

Thin (45–50 nm) non-doped and doped (by Sb and Al) polycrystalline Mg stannide films consisting mainly of Mg2Sn semiconductor phase and containing small quantity of Mg2Si phase have been grown by multiple layer deposition at room temperature and single step annealing at 150 °C of the (Sn–Mg) bi-layers on Si(111) n-type wafers with 7.5 Ω·cm resistivity. Optical spectroscopy data have shown that the grown Mg stannide films is a semiconductor with direct band gap of 0.17 ± 0.03 eV, with second and third direct interband transitions at 0.34 ± 0.02 and 0.45 ± 0.04 eV. An undispersed refraction index: n0 = 3.78 ± 0.06 was calculated from phonon energy dependence of the refraction index of the grown films in the 0.12–0.20 eV energy range. Temperatures dependent Hall effect measurements have revealed about 0.28 eV electrical band gap value in the films.