Self-powered MoS₂/n-type GaN heterojunction photodetector with broad spectral response in ultraviolet–visible–near-infrared range

An MoS₂/n-type GaN 2-dimensional (2D)/3-dimensional (3D) hybrid heterojunction photodiode was fabricated by layer transfer of a large-scale grown MoS₂ film on a GaN substrate. The MoS₂/n-type GaN heterojunction photodiode was highly sensitive to ultraviolet (UV) light with a responsivity of 1.28 × 10⁶ and 28.18 AW^–1 under the illumination of incident light with a wavelength of 365 nm at a forward and reverse voltage of ± 3 V, respectively. The detectivity and noise-equivalent power of the photodiode were determined to be, respectively, 9.08 × 10¹⁴ cm·Hz^1/2·W^–1 and 5.50 × 10⁻⁵ pW·Hz^–1/2 at 365 nm and − 3 V bias with a rise/fall duration of 98/144 ms. Moreover, the photodiode exhibited a self-powered operation with pronounced photoresponse at zero bias having a responsivity of 0.05 AW⁻¹ at 365 nm. The MoS₂/n-type GaN heterojunction photodiode operated with outstanding stability and repeatability, spanning a wide wavelength range of the UV–near-infrared range, and exhibited a responsivity of 3.81, 0.73, and 0.09 AW⁻¹ at 550, 750, and 900 nm, respectively. The mechanism of carrier transport in MoS₂/n-type GaN photodiodes was thoroughly explained using energy band diagrams. This self-powered photodetector, with superior light harvesting and good photoresponse over a wide wavelength range of the UV–near-infrared regime and carrier transport behavior, is anticipated to open up a window for integration of 2D-layered transition-metal dichalcogenides/GaN heterojunction-based multiple-wavelength photodetectors.