Effect of substrate temperature on the growth of Nb3Sn film on Nb by multilayer sputtering

TL;DR

This study investigates how substrate temperature during multilayer sputtering affects the structural and superconducting properties of Nb3Sn films, revealing a trade-off between surface smoothness and critical temperature.

Contribution

It provides new insights into optimizing substrate temperature to improve Nb3Sn film quality and superconducting performance.

Findings

Highest Tc of 17.76 K at room temperature deposition

Smoother surface morphology at 250°C with Tc of 17.58 K

Substrate temperature influences film surface and superconducting properties

Abstract

Nb3Sn films were fabricated by multilayer sequential sputtering on Nb at substrate temperatures ranging from room temperature to 250 {\deg}C. The multilayers were then annealed inside a separate vacuum furnace at 950 {\deg}C for 3h. The films material properties were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and transmission electron microscopy. The films superconducting properties were studied by four-point probe resistivity measurements from room temperature to below the superconducting critical temperature Tc. The highest film Tc was 17.76 K, obtained when the multilayers were deposited at room temperature. A superconducting Nb3Sn thin film with a smoother surface morphology but a lower Tc of 17.58 K was obtained on the film deposited at a substrate temperature of 250 {\deg}C.