Ideal Superconducting Diode Effect in Topological Insulator Josephson Junction Devices

Superconducting diodes introduce nonreciprocal supercurrent transport, enabling rectification of supercurrents in quantum circuits. In this work, we develop a new on-chip stencil-mask fabrication technique for InP substrates. This approach enables the selective area growth of topological insulator (TI) Bi₂Te₃ thin films and the in situ formation of Josephson junction (JJ) devices within our molecular beam epitaxy (MBE) chamber. These in situ fabricated TI-based JJ devices exhibit a pronounced superconducting diode effect under an out-of-plane magnetic field. Under radio frequency (RF) irradiation at small magnetic fields, the diode efficiency can be tuned by RF power and reaches 100%, thereby realizing an ideal superconducting diode. The diode polarity can be reversed by a magnetic field of ~5 mT at an RF frequency of ~2.5 GHz, making the device highly compatible with superconducting quantum circuits. Our results demonstrate a controllable and ideal superconducting diode effect in TI-based JJ devices, establishing a pathway towards nonreciprocal superconducting components for quantum computation.