Tunable mid-infrared photodetector based on graphene plasmons controlled by ferroelectric polarization for micro-spectrometer.

Surface plasmonic detectors have the potential to be key components of miniaturized chip-scale spectrometers. Graphene plasmons, which are highly confined and gate-tunable, are suitable for in situ light detection. However, the tuning of graphene plasmonic photodetectors typically relies on the complex and high operating voltage based on traditional dielectric gating technique, which hinders the goal of miniaturized and low-power consumption spectrometers. In this work, we report a tunable mid-infrared (MIR) photodetector by integrating of patterned graphene with non-volatile ferroelectric polarization. The polarized ferroelectric thin film provides an ultra-high surface electric field, allowing the Fermi energy of the graphene to be manipulated to the desired level, thereby exciting the surface plasmon polaritons effect, which is highly dependent on the free carrier density of the material. By exciting intrinsic graphene plasmons, the light transmittance of graphene is greatly enhanced, which improves the photoelectric conversion efficiency of the device. Additionally, the electric field on the surface of graphene enhanced by the graphene plasmons accelerates the carrier transfer efficiency. Therefore, the responsivity of the device is greatly improved. Our simulations show that the detectors have a tunable resonant spectral response of 9-14 μ m by reconstructing the ferroelectric domain and exhibit a high responsivity to 5.67 × 10 5 A W -1 at room temperature. Furthermore, we also demonstrate the conceptual design of photodetector could be used for MIR micro-spectrometer application.