Anomalous and Polarization‐Sensitive Photoresponse of T_d‐WTe₂ from Visible to Infrared Light

Abstract

Recently, an emergent layered material T d -WTe 2 was explored for its novel electron-hole overlapping band structure and anisotropic inplane crystal structure. Here, the photoresponse of mechanically exfoliated WTe 2 flakes is investigated. A large anomalous current decrease for visible (514.5 nm), and mid-and far-infrared (3.8 and 10.6 µm) laser irradiation is observed, which can be attributed to light-induced surface bandgap opening from the first-principles calculations. The photocurrent and responsivity can be as large as 40 µA and 250 A W −1 for a 3.8 µm laser at 77 K. Furthermore, the WTe 2 anomalous photocurrent matches its in-plane crystal structure and exhibits light polarization dependence, maximal for linear laser polarization along the W atom chain a direction and minimal for the perpendicular b direction, with the anisotropic ratio of 4.9. Consistently, first-principles calculations confirm the angle-dependent bandgap opening of WTe 2 under polarized light irradiation. The anomalous and polarization-sensitive photoresponses suggest that linearly polarized light can significantly tune the WTe 2 surface electronic structure, providing a potential approach to detect polarized and broadband lights up to far infrared range.

2D Metal Chalcogenides for IR Photodetection

“…[59] Abnormally, a large anomalous current emerged in the Td-WTe 2 photodetector at the illumination of 3.8 µm due to light-induced surface bandgap opening. [59] Meanwhile, as an another important member of the 2D TMDs family, 2D HfS 2 (indirect bandgap ≈ 1.45 eV) shows remarkable optical response in IR detection. [60] As shown in Figure 3c, the HfS 2 phototransistor exhibits an ultrahigh responsivity in excess of 3.08 × 10 5 A W −1 , ultrahigh photogain exceeding 4.72 × 10 5 , and ultrahigh detectivity over 4 × 10 12 Jones, which is superior to the vast majority of the reported 2D TMDs-based IR phototransistors.…”

“…It happens that there is a similar case. Zhou et al have explored an emergent 2D layered material Td‐WTe 2 for polarization‐sensitive broadband photoresponse from visible to MIR . Abnormally, a large anomalous current emerged in the Td‐WTe 2 photodetector at the illumination of 3.8 µm due to light‐induced surface bandgap opening .…”

“…Zhou et al have explored an emergent 2D layered material Td‐WTe 2 for polarization‐sensitive broadband photoresponse from visible to MIR . Abnormally, a large anomalous current emerged in the Td‐WTe 2 photodetector at the illumination of 3.8 µm due to light‐induced surface bandgap opening . Meanwhile, as an another important member of the 2D TMDs family, 2D HfS 2 (indirect bandgap ≈ 1.45 eV) shows remarkable optical response in IR detection .…”

“…The photodetector utilized the plasmonic NIR resonance absorption in RWs and the high photoconductive gain from MoS 2 to achieve the detection ranging from 1000 to 1250 nm. [51] In addition to MoS 2 , many other 2D TMDs have been exploited for IR photodetection, including MoSe 2 , [52,53] MoTe 2 , [54][55][56] WSe 2 , [57,58] WTe 2 , [59] HfS 2 , [60] and PtSe 2 . [61] Ko et al have demonstrated a few-layer MoSe 2 -based NIR photodetector that possesses a high responsivity of 238 A W −1 under illumination of 785 nm, [52] several orders of magnitude higher than that of a device based on multilayer MoS 2 .…”

Designing Multicolor Dual‐Mode Lanthanide‐Doped NaLuF4/Y2O3 Composites for Advanced Anticounterfeiting

“…Thus, it is critical to develop more safe anticounterfeiting techniques that are easy to identify and difficult to imitate . In recent years, owing to the vigorous development of science and technology, various kinds of anticounterfeiting techniques have emerged, such as barcodes, radio frequency identification technology, laser holograms, and watermarks, which can effectively combat counterfeiting and safeguard brand holders. Unfortunately, the easy duplication features and high manufacturing costs of these anticounterfeiting technologies limit their applications.…”