Anisotropic Broadband Photoresponse of Layered Type‐II Weyl Semimetal MoTe₂

Abstract

Photodetectors based on Weyl semimetal promise extreme performance in terms of highly sensitive, broadband and self-powered operation owing to its extraordinary material properties. Layered Type-II Weyl semimetal that break Lorentz invariance can be further integrated with other two-dimensional materials to form van der Waals heterostructures and realize multiple functionalities inheriting the advantages of other two-dimensional materials. Herein, we report the realization of a broadband self-powered photodetector based on Type-II Weyl semimetal T -MoTe . The prototype metal-MoTe -metal photodetector exhibits a responsivity of 0.40 mA W and specific directivity of 1.07 × 10 Jones with 43 μs response time at 532 nm. Broadband responses from 532 nm to 10.6 μm are experimentally tested with a potential detection range extendable to far-infrared and terahertz. Furthermore, we identify the response of the detector is polarization angle sensitive due to the anisotropic response of MoTe . The anisotropy is found to be wavelength dependent, and the degree of anisotropy increases as the excitation wavelength gets closer to the Weyl nodes. In addition, with power and temperature dependent photoresponse measurements, the photocurrent generation mechanisms are investigated. Our results suggest this emerging class of materials can be harnessed for broadband angle sensitive, self-powered photodetection with decent responsivities.

Ultrahigh Stability 3D TI Bi2Se3/MoO3 Thin Film Heterojunction Infrared Photodetector at Optical Communication Waveband

“…Peculiarly, the rise time (τ on ) and fall time (τ off ) of Bi 2 Se 3 /MoO 3 heterojunction photodetector is 63 and 78 µs (62 and 76 µs) @ 1310 nm (@ 1550 nm), respectively. In electronic branch, the device's response time in this experiment can get up to 62 µs, which is the fastest Bi 2 Se 3 ‐based device as we know …”

“…In addition, the difficulty in preparation and stability of device are the premise of the device whether can be widely used in the future . To meet this requirement, the device must have a high success preparation rate when it is prepared on a large scale, as well as long‐term atmospheric environment stability . For this reason, we displayed the I ph response diagram of different device units on the same substrate @ 1550 nm, and found that the properties of different device units prepared in one time were basically consistent (Figure 4c).…”

2D Metal Chalcogenides for IR Photodetection

“…Chen and co‐workers demonstrated anisotropic broadband photoresponse in exfoliated multilayer Td‐MoTe 2 under photoexcitation in the range of 532 nm to 10.6 µm . The Weyl semimetal‐based photodetector exhibits a responsivity of 4.15 × 10 −5 A W −1 and specific directivity of 9.1 × 10 6 Jones with 32 µs response time at 10.6 µm . It happens that there is a similar case.…”

“…The excellent photoresponse is considered to be attributed to the high quality of as‐synthesized samples . Different from 3R‐MoTe 2 , a recently introduced 2D Td‐MoTe 2 is a Weyl semimetal in electron‐band structure and has in‐plane anisotropy in crystal structure . Chen and co‐workers demonstrated anisotropic broadband photoresponse in exfoliated multilayer Td‐MoTe 2 under photoexcitation in the range of 532 nm to 10.6 µm .…”

“…Different from 3R‐MoTe 2 , a recently introduced 2D Td‐MoTe 2 is a Weyl semimetal in electron‐band structure and has in‐plane anisotropy in crystal structure . Chen and co‐workers demonstrated anisotropic broadband photoresponse in exfoliated multilayer Td‐MoTe 2 under photoexcitation in the range of 532 nm to 10.6 µm . The Weyl semimetal‐based photodetector exhibits a responsivity of 4.15 × 10 −5 A W −1 and specific directivity of 9.1 × 10 6 Jones with 32 µs response time at 10.6 µm .…”