Creation of Antisite Defects in Monolayer MoS₂ and WS₂ via Proton Irradiation

Understanding the constraints behind the effective fabrication of stable and reliable optoelectronic and spintronic devices for space, defense, and energy applications, based on two-dimensional (2D) materials operating under harsh irradiation environments, is of great importance. Defects are known to be one of the most important factors that affect the functionality and performance of 2D materials-based devices. Nevertheless, it remains a challenge to engineer and control defects to tailor materials’ properties. Here, we present a comprehensive joint experiment–theory study on the generation and manipulation of individual point defects in monolayer MoS2 and WS₂ for the first time by varying proton irradiation energies. We quantitively discovered that both the density and the nature of defects can be modulated by the proton energy; high defect density was observed with lower proton irradiation energies. Three distinct defect types of vacancies, antisites, and adatoms were observed. In particular, creation and manipulation of antisite defects provide an alternative way to create and pattern spin qubits based on point defects. Our results demonstrate that the formation of defects can be controlled using various particle irradiation energies, leading to new opportunities for tuning the properties of 2D materials and fabricate reliable devices.