Formation of arsenic clusters in InAs nanowires with an Al₂O₃ shell

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Heterostructured nanowires (NWs) require thorough understanding of their thermal behavior and phase evolution for effective device application.
• Indium arsenide (InAs) NWs are promising materials, but their behavior under thermal stress, particularly within protective shells, needs detailed investigation.

Purpose of the Study:

• To investigate the intermediate states during the vaporization of InAs NWs encapsulated in an aluminum oxide (Al2O3) shell.
• To elucidate the formation mechanism and characteristics of arsenic (As) clusters during the thermal process.

Main Methods:

• In situ heating experiments within a transmission electron microscope (TEM).
• Quenching techniques to capture intermediate phases.
• Analysis of high-angle annular dark field (HAADF) imaging and energy-dispersive X-ray (EDX) spectroscopy.
• Ab initio molecular dynamics (AIMD) simulations.

Main Results:

• Confirmation of amorphous Al2O3 shell formation.
• Observation of independent As clusters within the Al2O3 shell.
• Identification of As clusters at the ends of InAs fragments after quenching.
• Theoretical demonstration of the As cluster formation process.

Conclusions:

• The study provides critical insights into the thermal degradation pathways of InAs NWs within Al2O3 shells.
• Understanding As cluster formation is essential for controlling phase evolution and optimizing NW performance in devices.
• AIMD simulations offer a valuable theoretical complement to experimental observations for nanoscale thermal processes.