Electrically Switchable Polarization in Bi2O2Se Ferroelectric Semiconductors

Atomically 2D layered ferroelectric semiconductors, in which the polarization switching process occurs within the channel material itself, offer a new material platform that can drive electronic components toward structural simplification and high-density integration. Here, a room-temperature 2D layered ferroelectric semiconductor, bismuth oxychalcogenides (Bi2 O2 Se), is investigated with a thickness down to 7.3 nm (≈12 layers) and piezoelectric coefficient (d33 ) of 4.4 ± 0.1 pm V-1 . The random orientations and electrically dependent polarization of the dipoles in Bi2 O2 Se are separately uncovered owing to the structural symmetry-breaking at room temperature. Specifically, the interplay between ferroelectricity and semiconducting characteristics of Bi2 O2 Se is explored on device-level operation, revealing the hysteresis behavior and memory window (MW) formation. Leveraging the ferroelectric polarization originating from Bi2 O2 Se, the fabricated device exhibits "smart" photoresponse tunability and excellent electronic characteristics, e.g., a high on/off current ratio > 104 and a large MW to the sweeping range of 47% at VGS = ±5 V. These results demonstrate the synergistic combination of ferroelectricity with semiconducting characteristics in Bi2 O2 Se, laying the foundation for integrating sensing, logic, and memory functions into a single material system that can overcome the bottlenecks in von Neumann architecture.