Interfacial Reaction and Diffusion at the One-Dimensional Interface of Two-Dimensional PtSe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) platinum diselenide (PtSe2) exhibits tunable band gaps, making it promising for near-infrared optoelectronics.
• High-temperature processing yields various platinum-selenide phases with different stoichiometries.

Purpose of the Study:

• Investigate high-temperature phase transitions in 2D PtSe2.
• Observe interfacial reactions and the Kirkendall effect in 2D PtSe2.
• Understand the role of Se vacancies in phase formation.

Main Methods:

• In situ scanning/transmission electron microscopy (STEM) for observing phase transitions.
• 4D STEM measurements to analyze strain variations.
• Analysis of activation energy for phase formation.

Main Results:

• Observed unique one-dimensional interfaces during the formation of Se-poor phases (PtSe, PtSe1-x) at PtSe2 crystal edges.
• Identified the Kirkendall effect in a 2D material system.
• Determined that Se vacancies mediate the phase transition process, evidenced by strain variations.

Conclusions:

• The 2D nature of PtSe2 is crucial for the observed interfacial phenomena.
• The Kirkendall effect in 2D PtSe2 offers new strategies for engineering 1D edge chemistry.
• This research provides insights for contact engineering in 2D material-based devices.