Doping and defects largely determine the device performance of conventional semiconductor materials. Similar to traditional semiconductors, in order to realize the application of two-dimensional transition metal dichalcogenides (TMDCs) materials in electronic, optoelectronic and photonic devices and other fields, it is necessary to controllable doping and defect modulation of this material, so as to tune the two-dimensional materials. The energy band structure, the type and concentration of carriers, and then realize the multifunctionalization of materials and device integration. Compared with traditional semiconductor materials, two-dimensional materials are only one or a few layers of atomic thickness, so there are only one-dimensional line defects and zero-dimensional point defects, and these defects seriously affect the optoelectronic properties of two-dimensional materials. Two-dimensional materials usually synthesized by chemical vapor deposition methods have different concentrations of intrinsic structural defects. How to control the type and concentration of defects in 2D materials to achieve their applications in optoelectronic devices and energy fields is an important challenge in the field of 2D materials research.
       Recently, the team led by researcher Xiao Kai from the Nano Center of Oak Ridge National Laboratory in the United States can not only realize the regulation of the energy band structure of two-dimensional materials and the type and concentration of carriers through the method of isoelectronic metal doping, but also can reduce The concentration of point defects, thereby improving the quality and performance of the material. Unlike doping electron-rich or electron-deficient elements, isoelectronic elements and matrix elements usually have similar electronic structures and properties, so doping such atoms into the lattice will reduce the introduction of dislocations and other defects caused by lattice mismatch , but due to the difference in electronegativity, it may also cause the potential difference in the lattice to modulate the carrier concentration. Xiao Kai's team realized the replacement of some molybdenum (Mo) atoms in the MoSe2 lattice by the isoelectronic element tungsten (W) in the process of chemical vapor deposition growth, thereby forming a WxMo1-xSe2 two-dimensional alloy material. Using high-angle annular dark-field scanning transmission electron microscopy (ADF-STEM), they directly observed Se vacancy defects and displaced W atoms in two-dimensional lattices and precisely measured their concentrations. They found that by W substitution doping, the concentration of Se vacancy defects can be reduced to about 50% of the original, thereby increasing the luminescence intensity of monolayer WxMo1-xSe2 by as much as 10 times compared with MoSe2. In addition, theoretical calculations prove that the isoelectronic element W doping can reduce the formation of deep-level defect states in monolayer MoSe2. This work provides us with a new idea and method to modulate the defects in 2D materials, thereby improving the quality and performance of the materials to realize the application of such materials in the field of optoelectronic devices and energy in the future.

       91cailiao.cn, an online store for low-dimensional materials of Juna Group, focuses on material services and mainly sells related laboratory consumables and tools represented by low-dimensional materials, such as various two-dimensional materials, one-dimensional materials, zero-dimensional materials, black phosphorus BP, graphene, nanotubes, HOPG, natural graphite NG, molybdenum disulfide MoS2, molybdenum diselenide MoSe2, tungsten disulfide WS2, hBN boron nitride crystal, black phosphorus, tungsten ditelluride WTe2, rhenium disulfide ReS2, Rhenium diselenide ReSe2 quantum dots, nanowires, nanoparticles, molecular sieves, PMMA... Actively provide more excellent low-dimensional materials for scientific research institutes and promote the research of new materials.