Enhanced UV Photodetection on Flexible Substrate Back-Gated Ferroelectric Field-Effect Transistor Utilizing Barium Titanate Modified with 2D WS₂ Channel

This study presents a back-gated ferroelectric field-effect transistor (FeFET) implemented on a flexible foil substrate, using barium titanate (BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) as the ferroelectric gate layer and a two-dimensional (2D) WS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> sensing layer to enhance UV photodetection. The device selectively responds to UV wavelengths through gate-to-source voltage modulation to achieve negative photoconductance (NPC), significantly improving the detection signal-to-noise ratio. A highly crystalline BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> nanoparticle film, deposited via the hydrothermal sol-gel, functions as a high-k gate dielectric. Its polarization reorientation generates switchable dipoles that boost capacitance and channel conductivity, enabling increased drain current at lower gate voltages. This enhanced charge storage and electric field modulation improves carrier density and reduces power consumption. Moreover, the integration of WS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> on BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> film further enhances performance by increasing charge mobility and UV light absorption, which leads to faster charge transport and improved sensitivity. The synergistic effect of WS<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> allows dynamic tuning of electronic properties, resulting in a remarkable responsivity of 19.8A/W. This design not only minimizes the threshold voltage but also provides superior electrostatic control over the channel, making it a promising approach for developing flexible, efficient photodetectors.