Mechanical exfoliation of h-BN as dielectric in Josephson junction fabrication

Among 2D materials, hexagonal boron nitride (h-BN) has been widely investigated as a promising substitute for metal oxide as a gate dielectric in quantum devices. Oxides are normally used as the gate dielectric, but the utilization of oxides creates charge traps at the interface of the surface channel and dielectric which leads to unintentional doping. Integrating h-BN as a gate dielectric can help reduce the doping due to its ideal characteristics such as its dangling-bond-free surface. Our method adopted in fabricating h-BN layers is mechanical exfoliation. In this method we split the bulk h-BN crystal into increasingly thinner flakes using the tapes and then transfer the target flakes onto Josephson junctions by temperature-controlled dry pick-up process. Further, we investigate how the utilization of h-BN will affect the electrical properties of Josephson Junctions with h-BN dielectric.