Ferroelectric Polarization Modulated Photodetection-Synaptic Integration Functions of a-GaO_<i>x</i>/Bi_0.85La_0.15FeO₃ Semiconductor–Ferroelectric Heterojunction

The switchover between photodetection and synaptic characteristics in a single device triggers immense potential in multiscene applications owing to friendly integration and low power consumption. Accordingly, a ferroelectric heterojunction optoelectronic device (FHOD) with controlled energy band structure by polarization switching is developed for programmable photoresponse to implement photodetection-synaptic integration functions. Herein, amorphous GaOx/Bi0.85La0.15FeO3 FHOD is characterized by flexible transformation between a self-powered photodetector (SPD) and an optoelectronic synaptic device (OSD) manifested by simply exerting bias voltage. Additional ferroelectric polarization switching offers a programmable dimension for modulating all-in-one metrics of SPD and OSD. When serving as SPD, the FHOD showcases boosted responsivity of 1.57 mA/W and detectivity of 5.3 × 1010 Jones under upward-polarization state, further expanding its application in simulating optical communication. When the FHOD serves as OSD under bias voltage, switchable ferroelectric polarization-assisted ferroelectric heterojunction determines synaptic weight update and relaxation characteristics of synaptic plasticity, such as enhanced paired-pulse facilitation index and pronounced memory retention level under the downward-polarization state. Based on OSD figures of merit, classical Pavlovian conditioning and color perception behavior are successfully emulated. Furthermore, the recognition accuracy of handwritten digits can reach up to 90.1%. This work proposes a promising scheme for developing all-in-one FHOD toward multiscene switching.