The Critical Temperature of Superconducting Aluminum Films

The R(T) dependences of thin superconducting aluminum films deposited on leucosapphire and gallium arsenide substrates by electron beam sputtering and molecular beam epitaxy have been experimentally studied. Regardless of morphology, a noticeable increase in the critical temperature of the superconducting transition with a decrease in the film thickness is found. The effect is interpreted as a manifestation of the quantum size effect.