Defect Engineering of MoS₂ for Room-Temperature Terahertz Photodetection

Two-dimensional (2D) materials have exotic intrinsic electronic band structures and are considered as revolutionary foundations for novel nanodevices. Band engineering of 2D materials may pave a new avenue to overcome numerous challenges in modern technologies, such as room temperature (RT) photodetection of light with photon energy below their band gaps. Here, we reported the pioneering RT MoS₂-based photodetection in the terahertz (THz) region via introducing Mo⁴⁺ and S^2- vacancies for rational band gap engineering. Both the generation and transport of extra carriers, driven by THz electromagnetic radiations, were regulated by the vacancy concentration as well as the resistivity of MoS₂ samples. Utilizing the balance between the carrier concentration fluctuation and carrier-scattering probability, a high RT photoresponsivity of 10 mA/W at 2.52 THz was realized in an Mo-vacancy-rich MoS_2.19 sample. This work overcomes the challenge in the excessive dark current of RT THz detection and offers a convenient way for further optoelectronic and photonic devices based on band gap-engineered 2D materials.