Compact chromium oxide thin film resistors for use in nanoscale quantum circuits

TL;DR

This study characterizes chromium oxide thin films with tunable resistance for potential use as on-chip resistors in nanoscale quantum circuits, emphasizing their electrical properties and interface compatibility.

Contribution

It provides detailed electrical characterization of oxygen-doped chromium oxide films and evaluates their interface contact resistance for quantum circuit applications.

Findings

Resistance varies from 28Ω/□ to 32.6kΩ/□ with oxygen doping.

Films exhibit ohmic behavior at all temperatures tested.

Gold layers improve contact resistance with chromium oxide.

Abstract

We report on the electrical characterisation of a series of thin chromium oxide films, grown by dc sputtering, to evaluate their suitability for use as on-chip resistors in nanoelectronics. By increasing the level of oxygen doping, the room-temperature sheet resistance of the chromium oxide films was varied from 28$\Omega / \square$ to 32.6k$\Omega / \square$. The variation in resistance with cooling to 4.2K in liquid helium was investigated; the sheet resistance at 4.2K varied with composition from 65$\Omega / \square$ to above 20G$\Omega / \square$. All of the films measured displayed ohmic behaviour at all measured temperatures. For on-chip devices for quantum phase-slip measurements using niobium-silicon nanowires, interfaces between niobium-silicon and chromium oxide are required. By characterising the interface contact resistance, we found that a gold intermediate layer is favourable: the specfic contact resistivity of chromium-oxide-to-gold interfaces was 0.15 m$\Omega$cm$^2$, much lower than the value for direct chromium-oxide to niobium-silicon interfaces, 65m$\Omega$cm$^2$. We conclude that these chromium oxide films are suitable for use in nanoscale circuits as high-value resistors, with resistivity tunable by oxygen content.