Abstract

Mid-infrared (MIR) photodetection, coveringdiverse molecular vibrational regions and atmospheric transmission windows, isvital to civil and military purposes. Versatile use of MIR photodetectors iscommonly dominated by HgCdTe alloys, InSb, and quantum superlattices, which arelimited by strict operation demands, high-cost, and environmental toxicity.Despite the rapid advances of black phosphorus (BP)-based MIR photodetectors,these are subject to poor stability and large-area integration difficulty.Here, the van der Waals (vdW) epitaxial growth of a wafer-scale 2D platinumditelluride (PtTe2) layer is reported via a simple tellurium-vaportransformation approach. The 2D PtTe2 layer possesses a unique mosaic-likecrystal structure consisting of single-crystal domains with highly preferential[001] orientation along the normal direction, reducing the influence ofinterface defects and ensuring efficient out-of-plane carrier transportation. Thischaracteristic, combined with the wide absorption of PtTe2 and well-designedvertical device architecture, makes the PtTe2/Si Schottky junctionphotodetector capable of sensing ultrabroadband light of up to 10.6 μm with ahigh specific detectivity. Also, the photodetector exhibits an excellentroom-temperature infrared-imaging capability. This approach provides a newdesign concept for high-performance, room-temperature MIR photodetection basedon 2D layered materials.