Defect identification in monolayer MoTe₂ through tunneling tip-induced charging and theoretical analysis

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Defects in transition metal dichalcogenides (TMDs) significantly influence their electronic, optical, and catalytic properties.
• Understanding these defects is crucial for both fundamental research and developing practical applications of TMDs.

Purpose of the Study:

• To investigate individual defects in a monolayer of molybdenum ditelluride (MoTe2) supported on graphene/Ir(111).
• To determine the electronic and structural characteristics of atomic-scale defects in MoTe2.

Main Methods:

• Utilized scanning tunneling microscopy (STM) to examine defects in MoTe2.
• Employed scanning tunneling spectroscopy (STS) to probe electronic properties.
• Combined experimental data with density functional theory (DFT) calculations for structural analysis.

Main Results:

• Observed charging rings at specific bias voltages, indicating ionization levels of doping centers relative to the Fermi level.
• While direct STM visualization of point defects was challenging, STS and DFT successfully identified the structural origins of observed charge states.
• Revealed insights into the electronic properties influenced by defects in MoTe2.

Conclusions:

• The study presents a powerful combined STM, STS, and DFT approach for characterizing atomic-scale defects in MoTe2.
• This methodology contributes to a deeper understanding of how defects dictate the electronic properties of transition metal dichalcogenides.