Fig. 2. The photoresponse of unbiased PdTe₂-based devices at 300 K.

(A) Schematic diagram of the PdTe₂-based photodetector. (B) The process of the PGE and its dependence on the polarized terahertz field. (i) Carrier scattering from scatters without terahertz field. (ii and iii) Ratchet scatterings under action of terahertz field with y and x polarizations. (C and D) The contributions of PGE and PDE in a single device under 0.48-meV terahertz excitation. (E) The impulse photocurrent response of the PdTe₂-based device after exposure to ambient atmosphere for 1 month (hυ ~ 0.48 meV and power density ~ 2.5 mW/cm²). (F) Display of rising and falling edges of the time-resolved response in a single period, exhibiting the video-rate time response at around 1 and 2.2 μs. a.u., arbitrary units. (G) Dependence of the photocurrent (black solid symbols, left axis) and the responsivity (red symbols, right axis) on the radiation power intensity. (H) The counts of unbiased devices with different magnitudes of photocurrent.