Optoelectronic Coincidence Detection with Two‐Dimensional Bi₂O₂Se Ferroelectric Field‐Effect Transistors

Abstract

Information processing with optoelectronic devices provides an alternative way to efficiently process hybrid optical and electronic signals. Ferroelectric field‐effect transistors (FeFETs) can effectively respond to external optical and electrical stimuli by modulating their polarization states. Here, a 2D FeFET is demonstrated by the epitaxial growth of high‐quality 2D bismuth layered oxyselenide (Bi2O2Se) films on PMN‐PT(001) ferroelectric single‐crystal substrates. Upon switching the polarization direction of PMN‐PT, the authors realize in situ, reversible, and nonvolatile manipulation of the resistance of Bi2O2Se thin film (≈877%). The device simultaneously exhibits a polarization‐dependent photoresponse through visible light (λ = 405 nm) and infrared light (IR, λ = 980 nm) illumination. Combining optical stimuli with ferroelectric gating, it is demonstrated that the devices not only show nonvolatile memory and optoelectronic responses, but also show coincidence detection of visible and IR light. This work holds great potential in constructing new multiresponse and multifunction 2D‐FeFETs.

Emerging Optical In‐Memory Computing Sensor Synapses Based on Low‐Dimensional Nanomaterials for Neuromorphic Networks

“…So far, more and more attention has been attached to both electrical‐control IMC and optical IMCS synapses based on low‐dimensional materials with the effect of ferroelectric polarization, especially for ferroelectric materials based on 2D van der Waals system such as PbZr 0.2 Ti 0.8 O 3 (PZT), Bi 2 O 2 Se, and α‐In 2 Se 3 . [ 114–119 ] However, no one has summarized the ferroelectric polarization mechanism of optical IMCS synapses with low‐dimensional materials. In this section, systematic discussions on the ferroelectric polarization mechanism of 2D materials optical IMCS synapses will be investigated for the first time.…”

“…[ 119 ] As there was no inversion symmetry in the 2D plane, the spontaneous polarization occurred in the direction of in‐plane, and the in‐plane polarization direction was also associated with the out‐plane polarization. [ 115,117–119 ] Therefore, the coupling modulation of the electric field direction and the polarization direction could be obtained, which was helpful to the transition process from semiconductor characteristics to metal‐like characteristics. [ 119 ]…”

“…Zheng et al proposed an optical IMCS synapse based on 2D ferroelectric Bi 2 O 2 Se materials, as illustrated in Figure a. [ 115 ] The electrical measurement had pointed out the n‐type semiconductor characteristic of the 2D ferroelectric Bi 2 O 2 Se thin film and the device showed a resistive ratio of 900%, which indicated that the nonvolatile modulation between the electric field and resistance could be obtained. As the illustrations in Figure 12b,c, when the external electric field was applied onto the gate terminal, polarized charges occurred on the top surface of the Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 (PMN‐PT) layer and influenced the carrier motion in the Bi 2 O 2 Se layer, which affected the electron density of the 2D ferroelectric Bi 2 O 2 Se thin film.…”

“…The changed conductance influenced by the pyroelectric effect and the ferroelectric polarization had a great impact on the following synaptic weight update. [ 115 ]…”

Bi2O2Se-based integrated multifunctional optoelectronics

“…50 Among various properties of Bi 2 O 2 Se, optical sensing has been widely explored in the development of phototransistors 45,47,51,52 and photodetectors. 49,53 In other recent reports, Bi 2 O 2 Se has been found in vast fields of applications: transistor, 54,55 polymer solar cell, 56 broad band photodetector (IR to THz), 57 coincidence detection, 58 and memristors. 59 Wu et al have explored high electron mobility and quantum oscillations in layered Bi 2 O 2 Se and fabrication of top gate FET showing ON/OFF ratio >10 6 and subthreshold swing 65 mV per decade (at room temperature) with Hall mobility 450 cm 2 V −1 s −1 .…”