Using the methods of Auger electron and photoelectron spectroscopy and light absorption spectroscopy, the composition, densities of state of electrons in the valence band, and parameters of the energy bands of Ge (111) implanted with Na+ ions with an energy of E0 = 0.5 keV at a dose of D = Dsat = 6·1016 cm-2 and a thin layer of NaGe2 obtained by heating ion-implanted Ge. It is shown that a narrow n-type band (~0.2 eV) appears in the Ge valence electron spectrum after ion implantation near the bottom of the conduction band, which is explained by the presence of a large number of unbound Na atoms in the ion-doped layer. NaGe2 nanofilms with a band gap of ~0.45 eV was obtained for the first time by heating ion-implanted Ge.