Optical Manipulation-Prepared Edge-Contacted MoTe2-NbS2 Heterojunction Photodetectors for High-Performance, Self-Powered, and Consistent Broadband Detection.

Abstract

Photodetectors, as fundamental components of modern optoelectronic systems, hold significant potential across various domains including communications, healthcare, and military reconnaissance. Heterojunctions play a crucial role in enhancing carrier separation through interface energy band engineering, thereby enabling high-performance detection. Furthermore, metal-semiconductor edge contacts can further optimize device performance, though conventional fabrication methods are often complex, time-consuming, and risk inducing material damage. A novel approach is proposed for realizing edge contact between 2D semiconductors and metals by using femtosecond laser-driven nanosheets moving on a substrate. MoTe2 and NbS2 nanosheets are precisely assembled into edge-contact heterojunction photodetectors by combining dry transfer techniques with optical manipulation. The device exhibits excellent responsivity (2 A W-1), specific detectivity (1.36 × 10⁸ Jones), and quantum efficiency (278%) at 900 nm. Moreover, this detector demonstrates a superior response speed over traditional top-contact detectors, achieving a response time of 30/46 µs and a response bandwidth of 5.4 kHz. Significantly, the detectors show broadband optical response spanning 280-1380 nm, with a consistent responsivity maintained between 280 and 1200 nm. The optical manipulation scheme also provides new solutions for the preparation of transverse heterojunction, customized edge-contact structure, and modulation of heterojunction junction area, which injects new momentum for the development of future optoelectronic devices.