Research Projects

Modern microelectronics face a significant challenge as energy consumption rises with increased demand for high-performance computing. Cryogenic operation has emerged as a promising strategy to reduce dynamic energy consumption. However, a critical bottleneck lies in the performance degradation of conventional semiconductor components, like p-n junction diodes, at low temperatures due to increased resistivity and energy loss from Joule heating. Superconducting diodes—quantum analogs of classical diodes—offer a revolutionary solution by enabling dissipationless current flow in one direction while maintaining high resistance in the opposite direction. This unidirectional superconducting current transport, known as the superconducting diode effect (SDE), has gained significant interest due to its potential applications in quantum computing, cryogenic memory, and next-generation electronics. Despite the initial theoretical predictions dating back decades, practical realization of a CMOS-compatible, voltage-tunable, and magnetic-field-free superconducting diode remains elusive. This project proposes the development of an all-nitride, wafer-scale superconducting-ferroelectric heterostructure leveraging a TiN/AlScN/TiN trilayer in a Josephson junction (JJ) geometry. The core innovation lies in employing ultrathin (~2 nm) ferroelectric AlScN as the tunnel barrier, which inherently breaks inversion symmetry and potentially time-reversal symmetry without requiring an external magnetic field. The use of TiN as the superconducting electrode and AlScN as the ferroelectric layer ensures compatibility with existing CMOS technology on 200-mm silicon wafers. Preliminary experiments confirm the feasibility of this approach. Superconducting TiN films with a critical temperature (~4.1 K) and high-quality TiN/AlScN multilayers with sharp interfaces have been successfully fabricated and characterized. This establishes a strong foundation for integrating voltage-controlled superconductivity into silicon platforms. Theoretical modeling and cryogenic transport measurements will be conducted in tandem to elucidate the mechanisms driving non-reciprocity, with particular attention to symmetry breaking induced by the ferroelectric barrier. The successful demonstration of this novel ferroelectric superconducting diode will introduce a transformative component for energy-efficient cryo-CMOS technologies. It also opens the pathway to novel device functionalities, such as dissipationless, non-volatile memory and gate-tunable superconducting elements critical for scalable quantum and classical information processing.