Superconducting transition temperature of cold-deposited indium films

The temperature dependence of the superconducting transition temperature T/sub c/ has been investigated for thin indium films (200--18 A), obtained by condensing the metal vapor in a vacuum better than 10-10 mm Hg onto a glass substrate cooled down to 2 K. As the thickness is decreased from 200 to 18 A, T/sub c/ increases from 4.20 to 4.65 K. The resistivity at the same time increases from 4 to 180 μΩxcm. The behavior of T/sub c/(d) is explained by the further softening of the phonon spectrum of cold-deposited indium films on reducing their thickness with a simultaneous increase in the electron--phonon coupling constant