High‐Performance Mixed‐Dimensional AlGaN/WS ₂ Heterojunction Photodiode Towards UV–vis Secure Communication

ABSTRACT Dual‐band photodetectors are pivotal for secure optical communication and intelligent spectral sensing, yet their development is often hindered by high power consumption, limited responsivity, and structural complexity, particularly in the ultraviolet (UV) regime. Here, we report a high‐performance UV–vis dual‐band photodetector based on a Type‐I mixed‐dimensional AlGaN/WS 2 heterojunction. Results reveal that forward‐bias‐induced interfacial polarity reversal drives a transition from depletion to accumulation mode, triggering a light‐assisted Fowler‐Nordheim tunneling mechanism that dynamically reshapes the tunneling barrier. Technology Computer‐Aided Design simulations substantiate this wavelength‐dependent barrier modulation. At V ds = 3 V, the device achieves exceptional responsivities of 164.8 A/W (365 nm) and 2.71 A/W (405 nm), along with specific detectivities of 5.57 × 10 13 Jones (365 nm) and 3.39 × 10 11 Jones (405 nm) calculated from the dark current. Simultaneously, the inherent band offsets of the Type‐I alignment effectively suppress carrier injection, maintaining a minimal dark current and yielding an ultra‐low noise‐equivalent power of 5.7 fW/Hz 1/2 . Leveraging these attributes, a wavelength‐multiplexed encrypted communication system was constructed, enabling independent modulation and secure dual‐channel transmission. This work introduces a new paradigm for interface‐engineered wavelength‐selective electronics and establishes a foundation for next‐generation wavelength‐encoded secure communication.