Abstract:
Aluminum films with a thickness of 120 nm and multilayer structures based on them were fabricated by the vacuum thermal evaporation method and experimentally studied. Unlike bulk samples, they demonstrated an order of magnitude higher resistivity up to 260 $\Omega$$\cdot$ nm and a doubled superconducting transition temperature of 2.3 K. It was shown that the observed features are due to both the chemical activity of aluminum and a decrease in the crystallite growth rate. It was found that when evaporating onto a Si(111) substrate cooled with liquid nitrogen, a decrease in the crystallite grain size from 50 nm to 15 nm and a decrease in the surface roughness to rms about 1 nm are observed. The measured transport properties of the studied cryogenic aluminum structures are associated with a decrease in the film thickness and the mean free path of electrons, the appearance of additional scattering of current carriers on oxide atoms, crystallite boundaries, structural defects, distortions and roughness of external and internal boundaries. The studies of films by AFM, SEM, STEM, EDXS, and X-ray diffraction methods showed a correlation between the microstructure and electrical parameters of the films. Keywords: thin films, crystalline structure, surface morphology, residual resistance, kinetic inductance.
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