Tuning Supercurrent in Josephson Field-Effect Transistors Using h-BN Dielectric.

Abstract

Epitaxial Al-InAs heterostructures appear as a promising materials platform for exploring mesoscopic and topological superconductivity. A unique property of Josephson junction field effect transistors (JJ-FETs) fabricated on these heterostructures is the ability to tune the supercurrent using a metallic gate. Here, we report the fabrication and measurement of gate-tunable Al-InAs JJ-FETs in which the gate dielectric in contact with the InAs is produced by mechanically exfoliated hexagonal boron nitride (h-BN) followed by dry transfer. We discuss a versatile fabrication process that enables compatibility between layered material transfer and Al-InAs heterostructures that allows us to achieve full gate-tunability of supercurrent by using only 5 nm thick h-BN flakes. Our study shows that pristine properties of epitaxial Josephson junctions, such as product of normal resistance and critical current, <i>I</i>_c<i>R</i>_n, are preserved. Furthermore, complementary measurements confirm that using h-BN dielectric changes the channel density less when compared to atomic layer deposition of Al₂O₃.