Natural formation of linear defect structures in MoS₂

Near surface defects can significantly impact the quality of metallic interconnects and other interfaces necessary to create device structures incorporating two-dimensional materials. Furthermore, the impact of such defects can strongly depend on their organization. In this study, we present scanning tunneling microscopy images and tunneling spectroscopy of point and linear defects near the surface of natural MoS₂. The point defects share similar structural and electronic characteristics and occur with comparable frequency as subsurface sulfur vacancies observed previously on natural MoS₂. The linear defects observed here occur less frequently than the point defects but share the same depth profile and electronic structure. These data indicate that the linear defects are actually a one-dimensional organization of subsurface sulfur vacancies. Our density functional calculations agree with this assessment in that, for sufficient local defect concentrations, it is energetically more favorable for the defects to be organized in a linear fashion rather than as clusters or even isolated single point defects. Given these measurements were taken from naturally formed MoS₂, this organization likely occurs during crystal formation. Considering the impact of one-dimensional organization on the local properties of layered materials, and the potential for them to be introduced purposefully during crystal formation, research into the formation mechanism and properties of these defects could enable new paths for defect engineering in MoS₂-based systems.. Authors: Lukashev, Pavel V. [University of Northern Iowa, Cedar Falls, IA (United States)] (ORCID:0000000225515954); Kidd, Timothy E. [University of Northern Iowa, Cedar Falls, IA (United States)] (ORCID:0000000208199400); Harms, Haley A. [University of Northern Iowa, Cedar Falls, IA (United States)] (ORCID:0009000046624730); Gorgen, Colin [University of Northern Iowa, Cedar Falls, IA (United States)]; Stollenwerk, Andrew J. [University of Northern Iowa, Cedar Falls, IA (United States)] (ORCID:0000000170831182). DOE Contract: SC0020334. Subjects: 2D materials; Schottky barriers; crystallization; crystallographic defects; density functional theory; depth profiling techniques; interfacial properties; scanning tunneling microscopy; spectroscopy