Superconductivity in planarised nanocrystalline diamond films

Area of Science:

• Materials Science
• Nanotechnology
• Superconductivity

Background:

• Boron-doped nanocrystalline diamond (B-NCD) films grown by chemical vapour deposition (CVD) offer high Young's modulus, making them suitable for superconducting nanoelectromechanical systems (NEMS).
• As-grown B-NCD films exhibit increasing surface roughness with thickness due to columnar growth, which can lead to intrinsic losses in NEMS devices.
• Reducing surface roughness through polishing is essential for improving the performance of B-NCD based NEMS.

Purpose of the Study:

• To investigate the effectiveness of chemical mechanical polishing (CMP) in reducing the surface roughness of B-NCD films.
• To assess the impact of CMP on the structural integrity and superconducting properties of B-NCD films.
• To enable the fabrication of high-quality superconducting NEMS using polished B-NCD films.

Main Methods:

• Chemical mechanical polishing (CMP) was applied to a 520 nm thick B-NCD film.
• Surface roughness was quantified using root-mean-square (RMS) measurements before and after polishing.
• The superconducting transition temperature (Tc) was measured to evaluate the effect of CMP on superconducting properties.

Main Results:

• CMP reduced the RMS surface roughness of the B-NCD film from 44.0 nm to 1.5 nm.
• The polishing process was completed within 14 hours without causing sample damage.
• CMP did not introduce significant changes to the superconducting transition temperature of the B-NCD film.

Conclusions:

• Chemical mechanical polishing is an effective method for significantly reducing surface roughness in B-NCD films.
• CMP preserves the structural integrity and superconducting properties of B-NCD films.
• This technique facilitates the use of B-NCD in the fabrication of high-performance superconducting NEMS.