Changsub Kim, Christina Bell, Jake M Evans, Jonathan Greenfield, Emma Batson, Karl K Berggren, Nathan S Lewis, Daniel P Cunnane
Author Information
Changsub Kim: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States. ORCID
Christina Bell: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States.
Jake M Evans: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States. ORCID
Jonathan Greenfield: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States.
Emma Batson: Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States. ORCID
Karl K Berggren: Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States. ORCID
Nathan S Lewis: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States. ORCID
Daniel P Cunnane: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States.
Progress in superconducting device and detector technologies over the past decade has realized practical applications in quantum computers, detectors for far-infrared telescopes, and optical communications. Superconducting thin-film materials, however, have remained largely unchanged, with aluminum still being the material of choice for superconducting qubits and niobium compounds for high-frequency/high kinetic inductance devices. Magnesium diboride (MgB), known for its highest transition temperature ( = 39 K) among metallic superconductors, is a viable material for elevated temperature and higher frequency superconducting devices moving toward THz frequencies. However, difficulty in synthesizing wafer-scale thin films has prevented implementation of MgB devices into the application base of superconducting electronics. Here, we report ultrasmooth (<0.5 nm root-mean-square roughness) and uniform MgB thin (<100 nm) films over 100 mm in diameter and present prototype devices fabricated with these films demonstrating key superconducting properties including an internal quality factor over 10 at 4.5 K and high tunable kinetic inductance in the order of tens of pH/sq in a 40 nm thick film. This advancement will enable development of elevated temperature, high-frequency superconducting quantum circuits, and devices.
