The dualism between adatom- and vacancy-based single crystal growth models.

Area of Science:

• Surface science and materials science, focusing on crystal growth dynamics.

Background:

• Established growth morphologies in homoepitaxial crystal growth include step-flow, layer-by-layer, mound formation, and random growth.
• Mound formation is crucial for nano-scale surface patterning, but similar phenomena occur in ion bombardment and etching.

Purpose of the Study:

• To explore the dualism between adatom and vacancy growth modes in crystal surface evolution.
• To theoretically and experimentally verify the existence of vacancy-based growth morphologies analogous to adatom-based ones.

Main Methods:

• Theoretical derivation of equations for mound formation considering both adatom and vacancy growth.
• Analytical solution for the growth shape evolution during simultaneous adatom and vacancy deposition.
• Experimental verification using a system where both adatom and vacancy mound formation are active.

Main Results:

• Demonstrated the existence of vacancy growth modes as the dual counterpart to standard adatom growth modes.
• Derived theoretical equations for mound formation, showing inverse similarity for vacancy growth.
• Achieved excellent agreement between the theoretically predicted mound shape and experimental observations.

Conclusions:

• Confirms the theoretical prediction of dualism between adatom and vacancy growth mechanisms.
• Highlights the applicability of particle/anti-particle formalisms to understand crystal growth.
• Provides a unified framework for understanding nano-scale surface patterning through mound formation.