Defect-Induced Vibration Modes of Ar+ -Irradiated MoS2

MoS${}_{2}$ is a prominent candidate among two-dimensional materials for future nanoelectronics, in which device performance depends crucially on the defect properties of the material. The authors show that in MoS${}_{2}$, vacancy defects give rise to Raman-active vibrational modes that uniquely identify missing Mo or S atoms, or larger vacancy clusters. Thus, Raman spectroscopy plus first-principles calculation emerges as a powerful tool to observe and identify vacancy defects in layered electronic materials, for device optimization and quality assurance.