Dislocation driven spiral and non-spiral growth in layered chalcogenides

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Two-dimensional (2D) materials offer potential for advanced electronic and photonic devices.
• Precise control over film thickness during epitaxial growth is a significant challenge for industrial applications.
• Uncontrolled multilayer growth disrupts theoretical expectations and breaks crystal inversion symmetry.

Purpose of the Study:

• To elucidate the underlying mechanism of unconventional multilayer growth in the epitaxy of layered materials.
• To identify the specific conditions that promote non-ideal growth modes.
• To provide guidelines for achieving controlled layer-by-layer growth.

Main Methods:

• Multiscale theoretical investigation combined with experimental evidence.
• Analysis of mechanistic similarities between multilayer concentric and spiral growth.
• Experimental demonstration and simulations to study driving forces and defect formation.

Main Results:

• Multilayer growth is driven by both chalcogen deficiency (leading to metal clustering) and excess (creating step edges).
• Identified specific nucleation defects and in-domain step edges contributing to multilayer formation.
• Revealed mechanistic parallels between different non-ideal growth modes.

Conclusions:

• Understanding the roles of chalcogen stoichiometry is key to controlling 2D material epitaxy.
• Findings offer practical guidelines for optimizing growth conditions.
• Enables large-area, layer-by-layer growth for next-generation device fabrication.