Polarization Signal Amplification of 2D GeSe-Based Polarization-Sensitive Photodetectors.

Polarization-sensitive photodetectors, resolving light intensity, wavelength, and polarization states, enable the characterization of probing microstructure, internal stress, and compositional heterogeneity. Polarizer-free polarization-sensitive photodetectors based on in-plane anisotropic 2D semiconductors offer potential for device miniaturization and on-chip integration, owing to their inherent linear dichroism and orientation-dependent carrier mobilities. Hundreds of in-plane anisotropic 2D materials have been successfully discovered; however, the limited anisotropic photocurrent ratio (PR<10) has hindered the practical application. Herein, a field-effect transistor (FET)-based amplification strategy, enhancing PR from 2.1 to 54.8 in 2D GeSe photodetectors is proposed. This significant PR enhancement arises from polarization-induced resistance variations dynamically modulating gate potentials. Coupled with a steep transistor subthreshold region, small gate fluctuations produce substantial drain current changes, amplifying output anisotropy sensitively. Evaluating four types of FET identifies SMT-Si transistors as optimal due to their high stability, sharp subthreshold, and excellent noise immunity. In addition, the amplified PR signal directly enhances image contrast and recognition accuracy. Notably, with a high-PR signal, the machine learning model achieves a recognition rate of 0.99 in only 17 training epochs, reflecting a computational cost reduction of over 60%. This work provides an effective strategy to enhance PR, benefiting from high-resolution polarization imaging and advanced optoelectronic sensing.