A Centimeter‐Scale Type‐II Weyl Semimetal for Flexible and Fast Ultra‐Broadband Photodetection from Ultraviolet to Sub‐Millimeter Wave Regime

Abstract

Flexible photodetectors with ultra-broadband sensitivities, fast response, and high responsivity are crucial for wearable applications. Recently, van der Waals (vdW) Weyl semimetals have gained much attention due to their unique electronic band structure, making them an ideal material platform for developing broadband photodetectors from ultraviolet (UV) to the terahertz (THz) regime. However, large-area synthesis of vdW semimetals on a flexible substrate is still a challenge, limiting their application in flexible devices. In this study, centimeter-scale type-II vdW Weyl semimetal, T d -MoTe 2 films, are grown on a flexible mica substrate by molecular beam epitaxy. A self-powered and flexible photodetector without an antenna demonstrated an outstanding ability to detect electromagnetic radiation from UV to sub-millimeter (SMM) wave at room temperature, with a fast response time of ≈20 μs, a responsivity of 0.53 mA W −1 (at 2.52 THz), and a noise-equivalent power (NEP) of 2.65 nW Hz −0.5 (at 2.52 THz). The flexible photodetectors are also used to image shielded items with high resolution at 2.52 THz. These results can pave the way for developing flexible and wearable optoelectronic devices using direct-grown large-area vdW semimetals.

Low-dimensional van der Waals materials for linear-polarization-sensitive photodetection: materials, polarizing strategies and applications

“…Importantly, the corresponding BP device array presents satisfactory device-to-device variation. Most recently, Yang et al have synthesized centimeter-scale T d -MoTe 2 film on a flexible mica substrate by molecular beam epitaxy [119]. From this perspective, 2D vdWMs are more suitable for the chip-scale integrated polarization optoelectronics.…”

Research progress on topological material-based photodetectors

“…Notably, a significant breakthrough has recently been achieved in this regard. Through MBE techniques, Yang et al 113 successfully grew centimeter-scale T d -MoTe 2 films on flexible mica substrates. This result has introduced fresh possibilities for the application of MoTe 2 in the field of photodetection.…”

Self-Powered Broadband Photodetectors Based on Large-Scale Continuous Films of Weyl Semimetal WTe2

“…As a pioneer, the graphene optoelectronic device has drawn the attention of researchers to topological semimetallic materials with zero band gaps. − It was found that the energy band structure of the topological semimetals exhibits unique Weyl points or Dirac points, resulting in distinctive energy band crossings and linear dispersion relationships. − Such unique electronic structures enable efficient photoelectric conversion and broadband optical detection that is not limited by the band gap like that in 2D semiconductors. Moreover, the carriers in topological semimetallic materials exhibit high mobility within the crystal, enhancing the efficiency of electron–photon interactions in photoelectric devices. − It could minimize the dissipation during the photoelectric conversion process, thus giving rise to high detection sensitivity and faster response speed. − Additionally, compared to the PDs fabricated on exfoliated 2D materials, the PDs based on large-scale continuous films of 2D semimetals could have larger photosensitive areas and form a device array on the same wafer, which is particularly advantageous for applications. , …”