Atomistic Positioning of Defects in Helium Ion Treated Single-Layer MoS2

Abstract

Structuring materials with atomic precision is the ultimate goal of nanotechnology and is becoming increasingly relevant as an enabling technology for quantum electronics/spintronics and quantum photonics. Here, we create atomic defects in monolayer MoS₂ by helium ion beam lithography with a spatial fidelity approaching the single atom limit in all three dimensions. Using low-temperature scanning tunneling microscopy (STM) we confirm the formation of individual point defects in MoS₂ upon He-ion bombardment and show that defects are generated within 9 nm of the incident helium ions. Atom-specific sputtering yields are determined by analyzing the type and occurrence of defects observed in high-resolution STM images and compared with Monte-Carlo simulations. Both theory and experiment indicate that the He-ion bombardment predominantly generates sulfur vacancies.