NbAl3/Al microlaminated thin films deposited by UV laser ablation

NbAl3/Al microlaminated multilayer thin films were obtained by a laser abla tion deposition method, using a KrF excimer laser (lambda = 248 nm) at a fl uence of 7.6 J/cm(2). Films were deposited on Si substrates cooled during d eposition by liquid nitrogen flow in order to minimize crystal growth and i nterdiffusion between NbAl3 and Al layers. A helium gas flow to the middle portion of substrate and target was maintained at varying ambient pressure conditions (0, 100, 200 mtorr). Microstructures of the films produced were studied by scanning electron microscopy (SEM), transmission electron micros copy (TEM), and scanning transmission electron microscopy (STEM). With no h elium backpressure, films exhibited an amorphous structure, but with increa sing He pressure, the crystallinity of the films increased. TEM investigati ons determined the average aluminum crystal size to be approximately 30 nm, and each layer thickness to be 80 nm. STEM/EDS (electron dispersive spectr oscopy) analysis showed no significant interdiffusion between NbAl3 and Al layers. (C) 2001 Elsevier Science B.V. All rights reserved.