Tuning supercurrent in Josephson field effect transistors using h-BN dielectric: Part 1, Fabrication*

The transparent interface of epitaxial Al-InAs heterostructures provides an excellent platform for potential advances in topological superconductivity and superconducting quantum computation. We report the fabrication of gate-tunable Al-InAs Josephson junctions in which the gate dielectric in contact with the InAs is mechanically exfoliated hexagonal boron nitride (hBN). We discuss the fabrication process that enables compatibility between layered material transfer and Al-InAs heterostructures to avoid chemical reactions and unintentional doping that could affect the characteristics of the Josephson junction. We also discuss the effect of the thin hBN gate dielectric on the density of InAs Hall bars compared to ungated devices and devices with a more conventional AlOx dielectric.