Anisotropic point defects in rhenium diselenide monolayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) anisotropic materials like rhenium diselenide (ReSe2) are promising for novel electronic and optoelectronic devices.
• Defect engineering in 2D semiconductors is a key strategy to tailor their properties, but point defects in ReSe2 remain underexplored.

Purpose of the Study:

• To systematically investigate the atomic structure, formation energies, and electronic impact of various point defects in 1T″-ReSe2.
• To understand the dynamics of selenium vacancies under electron beam irradiation.
• To explore the potential of defect engineering for tuning the electronic and magnetic properties of ReSe2.

Main Methods:

• Atomic-scale imaging using transmission electron microscopy (TEM).
• First-principles calculations using density functional theory (DFT) to determine defect formation energies and electronic structures.
• In-situ electron beam irradiation to study defect dynamics.

Main Results:

• Diverse point defects, including selenium vacancies, oxygen/sulfur substitutions, and antisite defects, were identified and quantified.
• Selenium vacancies introduce in-gap electronic states, which are suppressed by isoelectronic substitutions.
• Antisite defects were found to induce localized magnetic moments in ReSe2.

Conclusions:

• Point defects in 1T″-ReSe2 can be controllably engineered to modify its electronic and magnetic properties.
• This work provides fundamental atomic-scale insights into defect behavior in ReSe2, enabling future device applications.
• Defect engineering presents a viable pathway for unlocking new functionalities in anisotropic 2D semiconductors.