Uncooled Mid-Infrared Sensing Enabled by Chip-Integrated Low-Temperature-Grown 2D PdTe2 Dirac Semimetal

Next-generationmid-infrared (MIR) imaging chips demand free-coolingcapability and high-level integration. The rising two-dimensional(2D) semimetals with excellent infrared (IR) photoresponses are compliantwith these requirements. However, challenges remain in scalable growthand substrate-dependence for on-chip integration. Here, we demonstratethe inch-level 2D palladium ditelluride (PdTe2) Dirac semimetalusing a low-temperature self-stitched epitaxy (SSE) approach. Thelow formation energy between two precursors facilitates low-temperaturemultiple-point nucleation (& SIM;300 & DEG;C), growing up, and merging,resulting in self-stitching of PdTe2 domains into a continuousfilm, which is highly compatible with back-end-of-line (BEOL) technology.The uncooled on-chip PdTe2/Si Schottky junction-based photodetectorexhibits an ultrabroadband photoresponse of up to 10.6 & mu;m witha large specific detectivity. Furthermore, the highly integrated devicearray demonstrates high-resolution room-temperature imaging capability,and the device can serve as an optical data receiver for IR opticalcommunication. This study paves the way toward low-temperature growthof 2D semimetals for uncooled MIR sensing.