High‐Performance UV Photodetector Based on CuGaO ₂ ‐Decorated WS ₂ With Enhanced Responsivity and Ultrafast Response Time

High‐performance photodetectors (PDs) require compact design, low power consumption, and broadband operation. Single‐layer WS 2 , though a promising 2D semiconductor, faces limitations in practical photodetection due to its atomic thickness and narrow spectral absorption. Here, we demonstrate a p–n heterostructure photodetector based on p‐type CuGaO 2 (CGO) functionalized n‐type WS 2 , which significantly enhances UV detection capability. The synergistic effects of broadened optical absorption, interfacial charge transfer, and the built‐in electric field at the CGO/WS 2 junction enable efficient photocarrier generation and separation. Under 15 μW/cm 2 UV illumination and 5 V bias, the device achieves a responsivity of 3.5 A/W, detectivity of 5.86 × 10 11 Jones, and external quantum efficiency of 1.2 × 10 3 %, with noise equivalent power as low as 0.28 pW/(Hz) 1/2 . Furthermore, the heterostructure exhibits fast response times (rise/fall time 243/262 μs), demonstrating its potential for high‐sensitivity, low‐light UV photodetection applications. These results demonstrate a straightforward yet effective approach to addressing the inherent limitations of 2D transition metal dichalcogenide photodetectors, providing a promising pathway for the development of broadband, UV‐responsive, and energy‐efficient photodetection technologies suitable for next‐generation optoelectronic applications.