Characterization of top-gated topological insulator nanoribbon Josephson junctions grown by selective-area epitaxy

Topologically protected surface states in topological insulators (TIs) offer the possibility of realising topological superconductivity and hosting Majorana zero modes when proximitized by an s-wave superconductor (S). Hybrid devices with S-TI-S Josephson junctions (JJs) have been integrated into superconducting microwave circuits and provide a new platform for hybrid qubits and detecting topological superconductivity using circuit quantum electrodynamics [1]. Local gate control over the JJ carrier density would enable in-situ tuning of the Josephson energy and qubit frequency. Towards this goal we describe the fabrication and characterization of top-gated (Bi_0.06Sb_0.94)₂Te₃ TI nanoribbon JJs grown by selective-area epitaxy.