Ultrahigh-Sensitivity and Fast-Speed Solar-Blind Ultraviolet Photodetector Based on a Broken-Gap van der Waals Heterodiode.

Broad-bandgap semiconductor-based solar-blind ultraviolet (SBUV) photodetectors have attracted considerable research interest because of their broad applications in missile plume tracking, flame detectors, environmental monitoring, and optical communications due to their solar-blind nature and high sensitivity with low background radiation. Owing to its high light absorption coefficient, abundance, and wide tunable bandgap of 2-2.6 eV, tin disulfide (SnS 2 ) has emerged as one of the most promising compounds for application in UV-visible optoelectronic devices. However, SnS 2 UV detectors have some undesirable properties such as slow response speed, high current noise level, and low specific detectivity. This study reports a metal mirror-enhanced Ta 0.01 W 0.99 Se 2 /SnS 2 (TWS) van der Waals heterodiode-based SBUV photodetector with an ultrahigh photoresponsivity ( R ) of ∼1.85 × 10 4 AW -1 and a fast speed with rising time (τ r ) of 3.3 μs and decay time (τ d ) of 3.4 μs. Notably, the TWS heterodiode device exhibits a significantly low noise equivalent power of ∼1.02 × 10 -18 W Hz -1/2 and a high specific detectivity of ∼3.65 × 10 14 cm Hz 1/2 W -1 . This study provides an alternative method for designing fast-speed SBUV photodetectors with enormous potential in applications.