Graphene/PtSe/Pyramid Si van Der Waals Schottky Junction for Room-Temperature Broadband Infrared Light Detection

Uncooled infrared (IR) photodetection has attracted increasing research interest due to its important applications in civil and military fields. Recently, platinum diselenide (PtSe2), a newly discovered group-10 two-dimensional (2D) noble metal dichalcogenide (NMD) member, has emerged as an attractive candidate for highly sensitive IR photodetection due to its layer-dependent bandgap transition from semiconductor to semimetal, wide optical absorption, and high carrier mobility. Here, we demonstrate the successful assembly of PtSe2/pyramid Si mixed-dimensional van der Waals (vdW) Schottky junction with a graphene transparent electrode. Due to the novel vertical device structure with a graphene top contact, the photodetector achieves an appealing device performance, including an ultrabroadband response up to $10.6~\mu \text{m}$ , a high responsivity of 0.528 A/W, a large specific detectivity of ~1012 Jones, and a fast response time of $8.2~\mu \text{s}$ at zero bias voltage. More importantly, these findings have enabled the realization of an excellent room-temperature long-wave IR (LWIR) imaging capability and its utilization as an optical receiver in optical IR communication. Our work demonstrates a reliable approach to the construction of a high-performance Schottky junction device for room-temperature broadband IR photodetection.