Defects in Highly Anisotropic Transition-Metal Dichalcogenide PdSe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Understanding defects in 2D materials like Palladium Diselenide (PdSe2) is crucial for their electronic applications.
• Intrinsic vacancies significantly influence material properties.

Purpose of the Study:

• To comprehensively study the atomic and electronic structures of pristine PdSe2 and its intrinsic vacancy defects.
• To investigate the imaging capabilities of scanning tunneling microscopy (STM) for sublayer defects.

Main Methods:

• Combined experimental techniques: Scanning Tunneling Microscopy (STM) and Spectroscopy.
• Theoretical calculations: Density Functional Theory (DFT).

Main Results:

• Identified sublayer Pd atoms and intrinsic Pd (V_Pd) and Se (V_Se) vacancy defects.
• V_Se and V_Pd defects create states near the Fermi level, enabling negative charging via tip gating.
• Charged vacancies induce distinct topographical features (disk-like for V_Pd, crater-like for V_Se) in STM images.
• STM can visualize sublayer defects up to 1 nm deep due to charge localization and magnification effects.

Conclusions:

• Scanning probe microscopy, with tip gating, offers a non-destructive method for characterizing sublayer defects.
• This technique enhances the understanding of defect-induced electronic and structural modifications in 2D materials.