A Top Floating Gate Heterojunction Structure for Integrated Photoelectric Computing and Low Voltage Memory

Multifunctional optoelectronic devices integrating sensing, computing, and memory hold significant implications for the advancement of high-density integrated systems and intelligent information processing. In this study, we propose a top floating-gate heterojunction field-effect transistor (TFG-HJFET) based on a MoS2/Ge heterojunction. This device exhibits positive photoconductivity under visible light and negative photoconductivity under near-infrared (NIR) light, respectively, enabling the composite functions of wide-spectrum fast sensing, high-integration computing, and low-power memory. For the computing function, we leverage the gate electric field and visible/NIR light modulation to enable the single TFG-HJFET to implement five basic logic operations as well as complex logic operations. Compared with traditional CMOS-based systems, this single-device design reduces transistor count by 50–97.5%. To further validate its practicality, we constructed an 8-bit parallel array, which verified the device’s feasibility for image edge detection and reversible encryption/decryption. In terms of memory performance, the TFG-HJFET achieves stable memory with an equivalent on–off ratio using only 1/3 of the gate voltage pulse required by conventional floating-gate structures, and no performance degradation is observed over a short period. Additionally, controlling the gate voltage enables distinguishable two-bit memory, which reduces the memory cell requirement per character by 50%. These results demonstrate that this integrated sensing-computing-memory design provides opportunities for the development of high-performance intelligent information processing systems, holding broad prospects in real-time image processing, secure communication, and information memory.