STRUCTURAL, ELASTIC AND TRANSPORT-PROPERTIES OF AG/AL MULTILAYER THIN-FILMS PREPARED BY ION-BEAM SPUTTERING

Multilayers of Ag/Al with composition modulation wavelengths lambda between 13.5 and 210 angstrom were deposited onto silicon substrates using ion-beam sputtering. X-ray diffraction scans showed well defined small angle peaks and satellite peaks at high angles indicating coherent multilayers. The average lattice parameter showed a 1.1% reduction with decreasing modulation wavelengths from 90 to 25 angstrom. Brillouin-scattering measurements showed a moderate 5% enhancement of surface velocity (elastic constant) with decreasing wavelengths. This elastic hardening and interplanar structural contraction may be partially attributed to the observed formation of Ag2Al at the multilayer interfaces. Although deposited only 10 from a normal incidence, the electrical resistivities, measured between 77 and 300 K in a van der Pauw configuration, showed a temperature independent in-plane anisotropy of up to 90% and the room temperature resistivity was an order of magnitude greater than expected from the bulk average. The temperature coefficient of resistivity showed a "U" shaped dependence with lambda and the lower up turn occurred at lambda almost-equal-to 50 angstrom.