Tuning supercurrent in Josephson field effect transistors using h-BN dielectric

• Published in: arXiv.org 2021-01
• Main Authors: Barati, Fatemeh, Thompson, Josh P, Dartiailh, Matthieu C, Sardashti, Kasra, Mayer, William, Yuan, Joseph, Wickramasinghe, Kaushini, Watanabe, K, Taniguchi, T, Churchill, Hugh, Shabani, Javad
• Format: Article
• Language: English
• Subjects: Boron nitride; Chemical reactions; Critical current (superconductivity); Dielectrics; Field effect transistors; Heterostructures; Indium arsenides; Josephson junctions; Semiconductor devices; Silicon; Superconductivity; Transistors
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2007.12202

The transparent interface in epitaxial Al-InAs heterostructures provides an excellent platform for potential advances in mesoscopic and topological superconductivity. Semiconductor-based Josephson Junction Field Effect Transistors (JJ-FETs) fabricated on these heterostructures have a metallic gate that tunes the supercurrent. 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 using a van der Waals-mediated pick up process. 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 JJ-FET. We achieve full gate-tunablity of supercurrent by using only 5~nm thick h-BN flakes. We contrast our process with devices fabricated using a conventional AlO\(_{\rm x}\) gate dielectric and show that h-BN could be an excellent competing dielectric for JJ-FET devices. We observe that the product of normal resistance and critical current, I\(_{\rm c}\)R\(_{\rm n}\), is comparable for both types of devices, but strikingly higher R\(_{\rm n}\) for the h-BN-based devices indicating that the surface is doped less compared to AlO\(_{\rm x}\) gate dielectric.