Multifunctional 2D FETs exploiting incipient ferroelectricity in freestanding SrTiO₃ nanomembranes at sub-ambient temperatures

Incipient ferroelectricity bridges traditional dielectrics and true ferroelectrics, enabling advanced electronic and memory devices. Firstly, we report incipient ferroelectricity in freestanding SrTiO₃ nanomembranes integrated with monolayer MoS₂ to create multifunctional devices, demonstrating stable ferroelectric order at low temperatures for cryogenic memory devices. Our observation includes ultra-fast polarization switching (~10 ns), low switching voltage (<6 V), over 10 years of nonvolatile retention, 100,000 endurance cycles, and 32 conductance states (5-bit memory) in SrTiO₃-gated MoS₂ transistors at 15 K and up to 100 K. Additionally, we exploit room-temperature weak polarization switching, a feature of incipient ferroelectricity, to construct a physical reservoir for pattern recognition. Our results showcase the potential of utilizing perovskite material properties enabled by advancements in freestanding film growth and heterogeneous integration, for diverse functional applications. Notably, the low 180 °C thermal budget for fabricating the 3D-SrTiO₃/2D-MoS₂ device stack enables the integration of diverse materials into silicon complementary metal-oxide-semiconductor technology, addressing challenges in compute-in-memory and neuromorphic applications.