Broadband Anisotropic Photoresponse of the “Hydrogen Atom” Version Type-II Weyl Semimetal Candidate TaIrTe₄

Abstract

The layered ternary compound TaIrTe is an important candidate to host the recently predicted type-II Weyl Fermions that break Lorentz invariance. Photodetectors based on Weyl semimetal promise extreme performance in terms of highly sensitive, broadband, and self-powered operation owing to its topologically protected band structures. In this work, we report the realization of a broadband self-powered photodetector based on TaIrTe. The photocurrent generation mechanisms are investigated with power- and temperature-dependent photoresponse measurements. The prototype metal-TaIrTe-metal photodetector exhibits a responsivity of 20 μA W or a specific detectivity of 1.8 × 10 Jones with 27 μs response time at 10.6 μm. Broadband responses from 532 nm to 10.6 μm are experimentally tested with potential detection range extendable to far-infrared and terahertz. Furthermore, anisotropic response of the TaIrTe photodetector is identified using polarization-angle-dependent measurement with linearly polarized light. The anisotropy is found to be wavelength dependent, and the degree of anisotropy increases as the excitation wavelength gets closer to the Weyl nodes. Our results suggest this emerging class of materials can be harnessed for broadband, polarization angle-sensitive, self-powered photodetection with reasonable responsivities.

Emerging in‐plane anisotropic two‐dimensional materials

“…Sun and coworkers reported the self‐powered polarization‐sensitive photodetector based on Type‐II Weyl semimetal candidate TaIrTe 4 . They found that the TaIrTe 4 ‐based photodetector can work over a broadband wavelength regime from 532 to 10.6 μm, and anisotropy ratio can reach 1.88 for mid‐infrared 10.6 μm, as shown in Figure G. Recently, Xu and coworkers for the first time demonstrated polarization‐dependent photodiode based on ReS 2 ‐ReSe 2 lateral heterostructure .…”

“…Xu and coworkers demonstrated that the photocurrent of these Re‐based dichalcogenides photodetectors show maximum values when the incident light is polarized along the b axis, and minimum values when the incident light is polarized perpendicular to b axis . Sun and coworkers reported the self‐powered polarization‐sensitive photodetector based on Type‐II Weyl semimetal candidate TaIrTe 4 . They found that the TaIrTe 4 ‐based photodetector can work over a broadband wavelength regime from 532 to 10.6 μm, and anisotropy ratio can reach 1.88 for mid‐infrared 10.6 μm, as shown in Figure G.…”

“…Reproduced with permission from ref. Copyright 2018, American Chemical Society. H, Anisotropic photocurrent response of GeP photodetectoralong the x ‐ and y ‐directions.…”

“…25,26 Since then, the polarizationdependent absorption, [26][27][28][29][30][31] Raman spectroscopy, [32][33][34] photoluminescence, [35][36][37] and the in-plane anisotropic electronic, 26,38,39 thermal, 40,41 and mechanical 42 properties of BP have been intensively studied. Ignited by BP, other inplane anisotropic 2D materials, from semimetals (T d WTe 2 , 43 1 T' MoTe 2,44,45 and ZrTe 5 46 TaIrTe 4 , 47,48 ) to semiconductors (group IV monochalcogenides, 49 Ta 2 NiS 5 , 50 GaTe, 51 group IVB trichalcogenides, 52 group IV-group V compounds, 53 70 TlSe, 71 ) (Table 1) and so on were explored. After developing for few years, the in-plane anisotropic 2D materials have becoming one of the most attractive research interests in the scientific field.…”

2D Metal Chalcogenides for IR Photodetection

“…Recently, 2D ternary materials have aroused a great research interest in many fields due to the adjustable physical properties by means of stoichiometric alteration . Such emerging 2D ternary materials also exhibit outstanding properties in IR detection . For example, ternary Ta 2 NiSe 5 is a direct bandgap semiconductor ( E g ≈ 0.36 eV), and it will maintain its direct bandgap nature when scaled down to monolayer .…”