Synergistic Dual Built-In Electric Fields Empower Mixed-Dimensional 1T'-MoTe2/WS2/p-GaAs Photodetectors with Field-Enhanced High Polarization Sensitivity for Intelligent Polarization-Encoded System.

Mixed-dimensional heterostructures represent an ideal platform for high-performance optoelectronics by integrating two-dimensional material with conventional semiconductors. However, synergistically balancing efficient charge separation, dark-current suppression, and polarization sensitivity remains a primary challenge for practical applications. Herein, a high-performance 1T'-MoTe2/WS2/p-GaAs dual-heterojunction photodetector is demonstrated by integrating a lateral 1T'-MoTe2/WS2 junction atop an isolated p-GaAs substrate. By the band-modulation effect of GaAs, back-to-back built-in electric fields are constructed at the interfaces. This dual-field synergistic mechanism enables dark-current suppression while significantly enhancing carrier separation efficiency, effectively mitigating the trade-off between noise suppression and signal collection in mixed-dimensional devices. Consequently, it achieves a responsivity of 0.24 A/W, an external quantum efficiency of 81.9%, and a specific detectivity of 4.94 × 1011 Jones under 365 nm illumination at zero bias. Driven by the carrier transport transition from diffusion to drift mode, the device exhibits field-enhanced polarization sensitivity, with the polarization ratio surging from 1.95 (0 V) to 3.69 (-2 V) under 405 nm illumination. By virtue of its excellent polarization characteristics, we demonstrate a proof-of-concept convolutional neural network-assisted intelligent polarization-encoded system with a recognition accuracy of 91.1%. This work reveals the physics of mixed-dimensional dual-heterojunctions, establishing a foundation for next-generation intelligent sensing and physical-layer information security.