boron-doped single-crystal diamond: an excellent candidate for high-performance SQUIDs

Superconducting quantum interference devices (SQUlDs) are currently used as magnetic flux detectors with ultra-high sensitivity for various applications such as medical diagnostics and magnetic material microstructure analysis, Single-crystalline superconducting boron-doped diamond is an excellent candidate for fabricating high-performance SQUlDs because of its robustness and high transition temperature, critical current density, and critical feld.

Boron-doped diamond also shows potential for fabricating high-performance superconducting devices such as SQUIDs and mechanical resonators. because of its excellent characteristics and processability described below, Diamond itself is an insulator; however, boron-doped diamond exhibits p-type conductivity and also exhibits superconductivity for doped boron concentrations greater than 3 x 1020 cm-3, Namely, the conductivity of diamond can be controlled from the insulating to superconducting state simply by changing the boron concentration.

Boron-doped diamond films can be epitaxially grown on single-crystalline and polycrystalline insulating diamond substrates. Thus, the fabrication of a superconducting circuit on an insulating substrate with good adhesion between the substrate and superconductor can be achieved. Moreover, growth of superconducting nanocrystalline diamond on silicon nitride has recently been reported, which opens a path towards the development of new diamond device applications. In addition to the above excellent characteristics, diamond exhibits strong tolerance to oxidation, heating, and physical scratches, and its microfabrication using oxygen plasma etching or selective epitaxial growth is easy. These characteristics suggest the suitability of superconducting diamond forvarious device applications such as scanning SQUID microscope and strong coupled hybrid quantum systems composed of nitrogen-vacancy centres, and superconducting circuits.

The boron-doped single-crystal diamond produced by CSMH can achieve doping from low concentration to high concentration. It has realized a uniform and controllable concentration and a customizable boron doping process.Lightly B-doped diamonds offer excellent carrier mobility, making them ideal substrates for semiconductor applications. Heavily B-doped diamonds provide low electrical resistance, serving as conductive electrodes for ohmic contacts.Furthermore, it is an ideal material for the fabrication of high-temperature, high-power semiconductor components and can also be used in electrochemistry.Additionally, CSMH offers high-quality diamond wafer substrates (e.g., on Si or SiC), enabling customers to develop advanced semiconductor devices.