Ferroelectric and Optoelectronic Coupling Effects in Layered Ferroelectric Semiconductor-Based FETs for Visual...

Controlling polarization states of ferroelectrics can enrich optoelectronic properties and functions, offering a new avenue for designing advanced electronic and optoelectronic devices. Here, ferroelectric semiconductor-based field-effect transistors (FeSFETs) are fabricated, where the channel is a ferroelectric semiconductor (e.g., α-In₂Se₃). Multiple conductance states are achieved in α-In₂Se₃-based FeSFETs by controlling the ferroelectric polarization. The on/off current ratio (I_on/I_off) is ≈10⁵ with a dark current of ≈10^-11 A by applying a single positive gate voltage pulse. Moreover, the device shows excellent endurance and retention performance. In a further step, the carrier transports and corresponding physics mechanism in various polarization states are studied by using Kelvin probe force microscopy (KPFM) and optoelectronic measurements. Finally, the α-In₂Se₃-based FETs can be trained. It can recognize handwritten digit images from MNIST dataset with a successful recognition accuracy of ≈95.5%. This work provides a new design idea and theoretical support for advanced optoelectronic devices in the field of in-memory sensing and computing.