Anisotropic ultrasensitive PdTe₂-based phototransistor for room-temperature long-wavelength detection

Emergent topological Dirac semimetals afford fresh pathways for optoelectronics, although device implementation has been elusive to date. Specifically, palladium ditelluride (PdTe₂) combines the capabilities provided by its peculiar band structure, with topologically protected electronic states, with advantages related to the occurrence of high-mobility charge carriers and ambient stability. Here, we demonstrate large photogalvanic effects with high anisotropy at terahertz frequency in PdTe₂-based devices. A responsivity of 10 A/W and a noise-equivalent power lower than 2 pW/Hz^0.5 are achieved at room temperature, validating the suitability of PdTe₂-based devices for applications in photosensing, polarization-sensitive detection, and large-area fast imaging. Our findings open opportunities for exploring uncooled and sensitive photoelectronic devices based on topological semimetals, especially in the highly pursuit terahertz band.