Self-powered, low-noise and high-speed nanolayered MoSe 2 /p-GaN heterojunction photodetector from ultraviolet to near-infrared wavelengths.

Integration of nanolayered metal chalcogenides with wide-bandgap semiconductors forming pn heterojunction leads to the way of high-performance photodetection. This work demonstrates the fabrication of a few nanometer thick Molybdenum diselenide (MoSe ₂ )/Mg-doped Gallium Nitride (p-GaN) heterostructure for light detection purposes. The device exhibits low noise broadband spectral response from ultraviolet to near-infrared range (300-950 nm). The band-alignment and the charge transfer at the MoSe ₂ /p-GaN interface promote self-powered photodetection with high photocurrent to dark current ratio of 2000 and 1000 at 365 nm and 640 nm, respectively. A high responsivity of 130 A W ^-1 , detectivity of 4.8 × 10 ¹⁰ Jones, and low noise equivalent power of 18 fW/Hz ^1/2 at 365 nm is achieved at an applied bias of 1 V. Moreover, the transient measurements reveal a fast rise/fall time of 407/710 μ sec for the fabricated device. These outcomes exemplify the viability of MoSe ₂ /p-GaN heterostructure for high-speed and low-noise broadband photodetector applications.
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