Controllable growth of type-II Dirac semimetal PtTe₂ atomic layer on Au substrate for sensitive room temperature terahertz photodetection

Platinum telluride (PtTe₂), a member of metallic transition metal dichalcogenides, provides a new platform for investigating various properties such as type-II Dirac fermions, topological superconductivity, and wide-band photodetection. However, the study of PtTe₂ is largely limited to exfoliated flakes, and its direct synthesis remains challenging. Herein, we report the controllable synthesis of highly crystalline 2D PtTe₂ crystals with tunable morphology and thickness via chemical vapor deposition (CVD) growth on Au substrate. By adjusting Te amount and substrate temperature, anisotropic and isotropic growth modes of PtTe₂ were realized on the solid and molten Au substrates, respectively. The domain size of PtTe₂ crystal was achieved up to 30 μm, and its thickness can be tuned from 5.6 to 50 nm via controlling the growth time. Furthermore, a metal–PtTe₂–metal structural device was fabricated to validate the wide-band terahertz (THz) photodetection from 0.04 to 0.3 THz at room temperature. Owing to the high crystallinity of PtTe₂ crystal, the photodetector acquires high responsivity (30–250 mA W^-1 from 0.12 to 0.3 THz), fast response rate (rise time: 7 μs, decay time: 8 μs), and high-quality imaging ability. Our work demonstrates the feasibility for realistic exploitation of high-performing photodetection system at THz band based on the CVD-grown 2D Dirac semimetal materials. © 2021 The Authors. InfoMat published by UESTC and John Wiley & Sons Australia, Ltd.