The electron-inelastic-scattering rate, 1/tau-in, is studied in superconducting amorphous-composite indium oxide films over substantial ranges of resistivity-rho-4.2 (1.4 less-than-or-equal-to rho-4.2 less-than-or-equal-to 9.8 m-OMEGA-cm), sheet resistance R square (0.17 less-than-or-equal-to R square less-than-or-equal-to 1.8 k-OMEGA), and reduced temperature T/T(co) (0.17 less-than-or-equal-to T/T(co) less-than-or-equal-to 0.6), using an electron tunneling technique. 1/tau-in(T) is obtained by a phenomenological analysis of the data. The main result is that 1/tau-in almost-equal-to 2.8 x 10(10) s-1[rho-4.2 (m-OMEGA-cm) T(co) (K)]3/2(T/T(co))3. That 1/tau-in is-proportional-to rho-4.2(3/2), as opposed to 1/tau-in is-proportional-to R square, indicates the films are three dimensional (3D) rather than 2D for inelastic scattering. A recent theory explains this result as inelastic electron-phonon scattering that is enhanced by disorder that is strong enough to suppress the normal-state density of states at the Fermi energy significantly.

By observing the nonuniform supercurrent density in wide superconducting thin films with a tunneling technique, we determine the perpendicular penetration depth ${\ensuremath{\lambda}}_{p}$ of the film. ${\ensuremath{\lambda}}_{p}$ has the predicted dependence on normalized temperature T/${T}_{c}$ and on sheet resistance ${R}_{\ensuremath{\square}}$, but is a factor of 1.5 to 2 larger than expected theoretically, even when strong electron-phonon coupling is taken into account.

Tunneling measurements on 3D amorphous composite indium plus indium-oxide films reveal anomalous features in the normal-state electron density of states ${N}_{n}$(E). Above 2 meV, ${N}_{n}$(E) increases linearly with ln(E) as expected for 2D films, rather than \ensuremath{\surd}E as expected for 3D films. However, the magnitude of the ln(E) term scales with resistivity ${\ensuremath{\rho}}_{4.2}$, not sheet resistance ${R}_{\ensuremath{\square}}$.