Phase segregation in AlInP shells on GaAs nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Core-shell nanowires are crucial for advanced electronic and optoelectronic devices.
• Understanding shell composition and morphology is key to controlling device performance.
• Aluminum Indium Phosphide (AlInP) on Gallium Arsenide (GaAs) nanowires offer unique properties for applications.

Purpose of the Study:

• To investigate the morphology and phase segregation of AlInP shells grown on GaAs nanowires.
• To identify the crystallographic origins and growth mechanisms of phase segregation.
• To determine the influence of growth temperature on facet formation and shell structure.

Main Methods:

• Photoluminescence spectroscopy on single core-shell nanowires to analyze shell composition.
• Cross-sectional scanning transmission electron microscopy (STEM) on thin slices to visualize phase segregation.
• Analysis of nanowire core and shell morphology.

Main Results:

• Photoluminescence indicated variations in AlInP shell composition.
• Phase segregation was confirmed, with Al-rich domains forming in <112> directions.
• Domain formation is linked to the meeting of {110} shell facets during growth.
• Side facet growth is temperature-dependent, forming {112} facets at low temperatures and {110} facets at high temperatures.

Conclusions:

• Phase segregation in AlInP shells on GaAs nanowires is driven by chemical potential variations and differential diffusion lengths.
• Growth temperature significantly influences the crystallographic facets ({112} vs. {110}) formed on the nanowire shell.
• The findings provide insights into controlling the composition and structure of semiconductor nanowires for tailored applications.