Recently, an emergent layered material T_d‐WTe₂ was explored for its novel electron–hole overlapping band structure and anisotropic inplane crystal structure. Here, the photoresponse of mechanically exfoliated WTe₂ 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 WTe₂ 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 WTe₂ under polarized light irradiation. The anomalous and polarization‐sensitive photoresponses suggest that linearly polarized light can significantly tune the WTe₂ surface electronic structure, providing a potential approach to detect polarized and broadband lights up to far infrared range.

中文翻译：

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Td-WTe2从可见光到红外光的异常和偏振敏感光响应

最近，人们对一种新兴的层状材料T _d -WTe ₂进行了研究，发现其具有新颖的电子-空穴重叠能带结构和各向异性的面内晶体结构。在这里，研究了机械剥离的WTe ₂薄片的光响应。观察到可见光（514.5 nm）以及中红外和远红外（3.8和10.6 µm）激光辐射的异常电流大大减小，这可以归因于第一性原理计算中光诱导的表面带隙开口。光电流响应度和可大为40μA和250 AW ^-1对于在77K 3.8微米激光此外，WTE ₂异常光电流与其面内晶体结构匹配，并表现出光偏振相关性，沿着W原子链a方向的线性激光偏振最大，而对于垂直b方向的线性激光偏振最小，各向异性比为4.9。一致地，第一性原理计算证实了偏振光照射下WTe ₂的角度依赖性带隙开口。异常和偏振敏感的光响应表明，线性偏振光可以显着调整WTe ₂表面电子结构，从而提供了一种潜在的方法来检测高达远红外范围的偏振光和宽带光。