Ferroelectric ultraviolet photodetector material with ultrafast response speed

Ferroelectric films are promising to be used for high-performance photodetectors due to their intrinsic electric fields and high dielectric constants. However, the presence of high-density domains with varying polarization directions can severely degrade comprehensive performance. Here, we fabricate high-quality SrAl_11-δTiO₁₉ (SATO) ferroelectric films through a solid-state reaction. The SATO film possesses a magnetoplumbite-type structure with polarization along the c-axis and exhibits the possibility of single-domain ferroelectrics. Ferroelectric performance tests show that the remnant polarization of SATO film reaches 7.8 μC/cm² and the polarization retention exceeds 500 hours. Optoelectronic performance measurements reveal that the SATO photodetector exhibits excellent performance with response wavelength of 330 nm, responsivity of 860 mA/W, detectivity of 1.63 × 10¹³ Jones, switching ratio of 1.9 × 10⁴, and ultrafast rise/fall response speed of 6.8 ns/17.7 ns (i.e., nearly 10000 times faster than traditional photodetectors). The outstanding properties highlight SATO as an outstanding candidate for next-generation photodetectors.