A Polarization-Sensitive Self-Powered Photodetector Based on a p-WSe₂/TaIrTe₄/n-MoS₂ van der Waals Heterojunction

Polarization-sensitive photodetection is highly appealing considering its great important applications. However, the inherent in-plane symmetry of a material and the single structure of a detector hinder the further development of polarization detectors with high anisotropic ratios. Herein, we design a p-WSe2/TaIrTe4/n-MoS2 (p–Ta–n) heterojunction. As a type-II Weyl semimetal, TaIrTe4 with an orthorhombic structure has strong in-plane asymmetry, which is confirmed by angle-resolved polarized Raman spectroscopy and second-harmonic generation. Due to the specific structure of the p–Ta–n junction with two vertical built-in electric fields, the device obtains a broadband self-powered photodetection ranging from visible (405 nm) to telecommunication wavelength (1550 nm) regions. Further, an optimized device containing 50–70 nm-thick layered TaIrTe4 has been realized. What is more, high-resolution imaging of “T” based on the device with clear borders illustrates excellent stability of the device. Significantly, the photocurrent anisotropic ratio of the p–Ta–n detector can reach 9.1 under 635 nm light, which is more than eight times that of the best known TaIrTe4-based photodetector reported before. This p–Ta–n junction containing a type-II Weyl fermion semimetal can provide an effective approach toward highly polarization-sensitive and high-performance integrated broadband photodetectors.