Infrared Responsivity of Pyroelectric Detectors With Nanostructured NiCr Thin-Film Absorber

This letter reports on the performance of LiTaO₃- based pyroelectric single-element detectors coated with a nanostructured thin-film absorber consisting of the same material as the sensor electrodes (NiCr). The fabrication of the absorber structure is achieved with a thermal evaporation technique in high vacuum. A major benefit is the one-step deposition and the functional integration of the sensor´s top electrode and the absorption layer enabled by a technologically simple deposition technique. The NiCr absorber shows a very high absorption efficiency comparable to that of metal-black coatings but with considerably higher mechanical robustness. The relative spectral responsivity of the detectors was evaluated in the 1-15 μm wavelength range showing good uniformity for a film thickness of about 1 μm.