Bias-induced giant enhancement of the anisotropic photoresponse of TaIrTe4 monolayer

The photogalvanic effect in topological semimetals offers a promising route for broadband polarization-sensitive photodetection, yet the influence of external bias has rarely been addressed, especially for highly anisotropic type-II Weyl semimetals such as TaIrTe4. Here, we report first-principles quantum transport calculations revealing that a modest bias voltage induces a giant, anisotropic enhancement of the photoresponse in monolayer TaIrTe4. Along the x-direction, the photoresponse increases by over two orders of magnitude across the entire infrared-to-visible spectrum. In contrast, the y-direction exhibits a weaker, non-monotonic, energy-selective enhancement governed by the discrete nature of its band dispersions. Transmission spectroscopy identifies the microscopic origin as bias-facilitated interband transitions between high-density-of-states regions proximate to the Fermi level. These findings establish TaIrTe4 as a highly tunable platform for directionally selective, infrared-compatible polarized photodetection.