Room temperature deposition of superconducting Niobium Nitride films by ion beam assisted sputtering

TL;DR

This study demonstrates room temperature ion beam assisted sputtering as an effective method to deposit niobium nitride films with enhanced superconducting properties, showing increased critical temperature and reduced nitrogen sensitivity.

Contribution

It introduces a novel room temperature deposition technique for NbN films that improves superconducting performance compared to traditional methods.

Findings

Films show higher critical temperature T_c with ion beam assistance.

Superconducting properties are less sensitive to nitrogen concentration.

Thickness dependence of T_c aligns with quantum size effects.

Abstract

We use room temperature ion beam assisted sputtering (IBAS) to deposit niobium nitride thin films. Electrical and structural characterizations were performed by electric transport and magnetization measurements at variable temperatures, X-ray diffraction and atomic force microscopy. Compared to reactive sputtering of NbN, films sputtered in presence of an ion beam show remarkable increase in the superconducting critical temperature T$_{\rm{c}}$, while exhibiting lower sensitivity to nitrogen concentration during deposition. Thickness dependence of the superconducting critical temperature is comparable to films prepared by conventional methods at high substrate temperatures and is consistent with behavior driven by quantum size effects or weak localization.