Crystal phase evolution in kinked GaN nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Seed-catalysed growth is ideal for tuning III-V nanowire (NW) crystal structures.
• Limited research exists on nitride NWs using this method.
• Gallium Nitride (GaN) NWs are crucial for electronic and optoelectronic applications.

Purpose of the Study:

• To demonstrate the controlled growth of epitaxial kinked wurtzite (WZ)/zinc-blende (ZB) heterostructure GaN NW arrays.
• To investigate the structural characteristics and phase evolution in GaN NWs.
• To provide insights into the growth mechanisms of WZ/ZB heterostructures.

Main Methods:

• Hydride vapour-liquid-solid vapour phase epitaxy (VLS-HVPE) under oxygen-rich conditions.
• Detailed structural analysis using advanced microscopy and diffraction techniques.
• Analysis of crystal phase distribution and defect structures.

Main Results:

• Successfully grew epitaxial kinked WZ/ZB heterostructure GaN NW arrays.
• Observed WZ and ZB phases throughout the GaN NWs.
• Identified stacking faults-free zones near tips and in kinked segments (>200 nm).
• Some NWs (<5%) exhibited phase boundaries leading to kinking and phase evolution.

Conclusions:

• A layer-by-layer growth mode is proposed to explain crystal phase evolution along phase boundaries.
• This work provides new insights into the controlled growth of WZ/ZB heterostructure GaN NWs.
• The findings contribute to the development of advanced GaN-based nanostructures.