Structure, bonding and electronic characteristics of amorphous Se

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Ovonic threshold switching (OTS) selectors enhance phase-change memory density and reduce leakage.
• Amorphous Germanium Selenide (GeSe) is a key OTS material, but its functional component, amorphous Selenium (Se), is understudied.
• Understanding amorphous Se is vital for optimizing Se-based OTS selector applications.

Purpose of the Study:

• To investigate the structure, bonding, and electronic properties of amorphous Selenium (Se).
• To elucidate the fundamental characteristics of amorphous Se relevant to its role in OTS devices.

Main Methods:

• Utilized *ab initio* molecular dynamics simulations.
• Analyzed atomic structure, bonding configurations, and electronic states.

Main Results:

• Identified a tendency for Se atoms to form 2-coordinated configurations, creating long, stable chains.
• Calculated a high Se-Se bond formation energy (4.44 eV), indicating significant bond stability.
• Observed mid-gap states in amorphous Se, linked to OTS behavior, despite their low proportion.

Conclusions:

• Amorphous Se exhibits stable chain structures with strong Se-Se bonds.
• The presence of mid-gap states confirms amorphous Se's potential for OTS applications.
• This research deepens the understanding of amorphous Se, supporting the development of advanced Se-based OTS selectors.