Atomistic Probing and Identification of Point Defects and Grain Boundaries of 1H and 1T′ Molybdenum Telluride Monolayer

The substantial structural defects frequently observed in fabricated transition-metal dichalcogenide (TMD) samples inevitably affect the device performance. The molybdenum telluride (MoTe₂) monolayer can easily generate phase transitions between the 1H and 1T' phases due to a small energy barrier. However, distinguishing and identifying various defects during experiments is challenging. In this study, we comprehensively explore point defects and grain boundaries in MoTe₂ using first-principles calculations. We simulate the corresponding scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) images to characterize different types of defects. The same type of point defects in the 1T' phase exhibits lower formation energies than those in the 1H phase. The grain boundaries of the 1T' phase form more easily, with corresponding formation energies ranging from 0.07 to 0.14 eV/Å. The partial densities of states indicate that the electronic properties of the 60°, 60°-glide, and 120° grain boundaries (GBs) in the 1T' phase are similar, while various types of defect rings in the 1H phase differ significantly. Our theoretical results effectively reduce the primary cost of characterizing defects and provide essential guidance for experimental references and identifications.