Crystal phase engineering of self-catalyzed GaAs nanowires using a RHEED diagram

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• III-V nanowires (NWs) crystal structure is influenced by catalyst droplet wetting angles.
• Tuning catalyst wetting angles is achievable via III and V flux.
• Controlling NW crystal structure is crucial for device applications.

Purpose of the Study:

• To present a method for controlling wurtzite (WZ) and zinc-blende (ZB) structures in self-catalyzed GaAs NWs.
• To utilize in situ reflection high-energy electron diffraction (RHEED) for structural analysis.
• To determine the critical wetting angle for structural transitions.

Main Methods:

• Growing self-catalyzed GaAs NWs using molecular beam epitaxy.
• Employing in situ RHEED to analyze diffraction patterns along the [11̄0] azimuth.
• Monitoring the intensity evolution of specific ZB and WZ diffraction spots during growth.
• Applying a semi-empirical model for NW growth analysis.

Main Results:

• Demonstrated control over the WZ and ZB crystal structures in GaAs NWs.
• Successfully realized ZB GaAs NWs with integrated controlled WZ segments.
• Correlated Ga flux variations with changes in WZ and ZB spot intensities.
• Deduced the critical wetting angle for structural transitions.

Conclusions:

• In situ RHEED analysis provides a viable method for controlling GaAs NW crystal structure.
• Ga flux is a key parameter for tuning the WZ/ZB ratio in NWs.
• The study provides insights into the fundamental mechanisms governing NW structural evolution.