Self-powered broadband photodetection enabled by facile CVD-grown MoS 2 /GaN heterostructures.

Achieving self-powered photodetection without biasing is a notable challenge for photodetectors. In this work, we demonstrate the successful fabrication of large-scale van der Waals epitaxial molybdenum disulfide (MoS 2 ) on a p-GaN/sapphire substrate using a straightforward chemical vapor deposition (CVD) technique. Our research primarily centers on the characterization of these photodetectors produced through this method. The MoS 2 /GaN heterojunction photodetector showcases a broad and extensive photoresponse spanning from ultraviolet A (UVA) to near-infrared (NIR). When illuminated by a 532 nm laser, its self-powered photoresponse is characterized by a rise time ( τ r ) of ∼18.5 ms and a decay time ( τ d ) of ∼123.2 ms. The photodetector achieves a responsivity ( R ) of ∼0.13 A W -1 and a specific detectivity ( D *) of ∼3.8 × 10 10 Jones at zero bias. Additionally, while utilizing a 404 nm laser, the photodetector reaches a maximum R and D * of ∼1.7 × 10 4 A/W and ∼1.6 × 10 13 Jones, respectively, at V b = 5 V. The operational mechanism of the device can be explained by the diode characteristics involving a tunneling current in the presence of reverse bias. The exceptional performance of these photodetectors can be attributed to the pristine interface between the CVD-grown MoS 2 and GaN, providing an impeccably clean tunneling surface. Additionally, our investigation has unveiled that MoS 2 /GaN heterostructure photodetectors, featuring MoS 2 coverage percentages spanning from 20% to 50%, exhibit improved responsivity capabilities at an external bias voltage. As a result, this facile CVD growth technique for MoS 2 photodetectors holds significant potential for large-scale production in the manufacturing industry.