Wafer-Scale MgB₂ Superconducting Devices

Area of Science:

• Materials Science
• Condensed Matter Physics
• Superconductivity

Background:

• Superconducting devices utilize materials like aluminum and niobium compounds.
• Magnesium diboride (MgB2) offers a high transition temperature (39 K) for elevated temperature applications.
• Synthesizing wafer-scale MgB2 thin films has been a significant challenge.

Purpose of the Study:

• To develop wafer-scale, ultrasmooth thin films of magnesium diboride (MgB2).
• To demonstrate the potential of these MgB2 films in fabricating advanced superconducting devices.
• To overcome limitations in current superconducting thin-film material choices.

Main Methods:

• Fabrication of ultrasmooth (<0.5 nm RMS roughness) and uniform MgB2 thin films (<100 nm) over 100 mm diameter wafers.
• Characterization of superconducting properties of the fabricated MgB2 films.
• Fabrication and testing of prototype superconducting devices using the developed MgB2 films.

Main Results:

• Achieved ultrasmooth and uniform MgB2 thin films suitable for large-scale fabrication.
• Demonstrated prototype devices with an internal quality factor >10^4 at 4.5 K.
• Observed high tunable kinetic inductance (tens of pH/sq) in 40 nm thick MgB2 films.

Conclusions:

• The developed MgB2 thin films are a promising material for next-generation superconducting electronics.
• This advancement facilitates the development of high-frequency and elevated-temperature superconducting quantum circuits.
• Enables new possibilities for superconducting devices in quantum computing and THz applications.