Fig. 4: High sensitivity of the MoSe₂/PdSe₂ heterostructure device at long-wave infrared (LWIR) spectral range at room temperature.

a Output curves (I_ds−V_ds) in dark and under 7.4 µm illumination with different power densities. Inset: Semi-logarithmic plot of I_ds−V_ds characteristic curves in dark and under 7.4 µm illumination with different power densities. b Output curves (I_ds−V_ds) in dark and under 10.6 µm illumination with different power densities. Inset: Semi-logarithmic plot of I_ds−V_ds characteristic curves in dark and under 10.6 µm illumination with different power densities. c Responsivities and detectivities at V_ds = 1 V under 7.4 and 10.6 µm light illuminations, respectively. d Room-temperature specific detectivity D* as a function of wavelength. The D* is compared with previously reported infrared 2D materials and the state-of-the-art LWIR photodetectors^{34,38,70,71,72}. The black dotted line represents the theoretical limits of D* calculated for the photodetectors operating under background-limited infrared performance (BLIP). The PC represents the photoconductive mode and SL represents the superlattice. FOV and T_b represent the field of view and background temperature, respectively. e Time-dependent photoresponse of the device under different polarized light illumination of 4.5 µm. The arrow represents the tendency for the photocurrent change as the angle of polarized light changes from 0° to 90°. f The polar plots of polarized photocurrents under 4.5 µm illumination.