Defect engineering of single- and few-layer MoS2 by swift heavy ion irradiation

We have investigated the possibility to use swift heavy ion irradiation for nano-structuring supported and freestanding ultra-thin MoS₂ samples. Our comprehensive study of the ion-induced morphological changes in various MoS₂ samples shows that depending on the irradiation parameters a multitude of extended defects can be fabricated. These range from chains of nano-hillocks in bulk-like MoS₂, and foldings in single and bilayer MoS₂, to unique nano-incisions in supported and freestanding single layers of MoS₂. Our data reveals that the primary mechanism responsible for the incisions in the ultrathin supported samples is the indirect heating by the SiO₂ substrate. We thus conclude that an energy of less than 2 keV per nm track length is sufficient to fabricate nano-incisions in MoS₂ which is compatible with the use of the smallest accelerators.