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

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 degrees C of the (Sn-Mg) bi-layers on Si(111) n-type wafers with 7.5 Omega 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: n(0) = 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. (C) 2015 The Japan Society of Applied Physics