Growth and Characterization of Polycrystalline NbO2 Thin Films on Crystalline and Amorphous Substrates

TL;DR

This study reports the fabrication and characterization of NbO2 thin films on different substrates, highlighting the importance of annealing in achieving crystallinity and the resulting changes in electrical resistivity relevant for memristor applications.

Contribution

It demonstrates a method to produce crystalline NbO2 thin films via RF-magnetron sputtering and post-deposition annealing, detailing how crystallinity affects electrical properties.

Findings

Crystalline NbO2 films have higher resistivity than amorphous ones.

Annealing parameters critically influence film crystallinity.

Crystalline films exhibit a resistivity increase by an order of magnitude.

Abstract

NbO2 is a potential material for nanometric memristor devices, both in the amorphous and the crystalline form. We fabricated NbO2 thin films using RF-magnetron sputtering from a stoichiometric target. The as-deposited films were amorphous regardless of the sputtering parameters. Post deposition vacuum annealing of the films was necessary to achieve crystallinity. A high degree of crystallinity was obtained by optimizing annealing duration and temperature. The resistivity of the material increases as it undergoes a structural transition from amorphous to crystalline with the crystalline films being one order of magnitude more resistive.