Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators

TL;DR

This paper investigates molybdenum rhenium alloy thin films for their superconducting properties and stability during carbon nanotube growth, enabling in situ integration of nanotubes with superconducting circuits.

Contribution

It demonstrates that co-sputtered MoRe films retain superconductivity and functionality of coplanar resonators under nanotube growth conditions, facilitating integrated nanotube-superconductor devices.

Findings

MoRe films exhibit superconductivity up to 15K.

Resonators remain functional during nanotube growth conditions.

Superconducting properties are characterized as a function of temperature.

Abstract

Molybdenum rhenium alloy thin films can exhibit superconductivity up to critical temperatures of $T_c=15\mathrm{K}$. At the same time, the films are highly stable in the high-temperature methane / hydrogen atmosphere typically required to grow single wall carbon nanotubes. We characterize molybdenum rhenium alloy films deposited via simultaneous sputtering from two sources, with respect to their composition as function of sputter parameters and their electronic dc as well as GHz properties at low temperature. Specific emphasis is placed on the effect of the carbon nanotube growth conditions on the film. Superconducting coplanar waveguide resonators are defined lithographically; we demonstrate that the resonators remain functional when undergoing nanotube growth conditions, and characterize their properties as function of temperature. This paves the way for ultra-clean nanotube devices grown in situ onto superconducting coplanar waveguide circuit elements.