Interplay between defect propagation and surface hydrogen in silicon nanowire kinking superstructures

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Semiconductor nanowire kinking superstructures with long-range structural coherence are difficult to fabricate.
• Understanding the mechanisms governing nanowire kinking is crucial for controlled synthesis.

Purpose of the Study:

• To investigate the reasons behind the difficulty in fabricating semiconductor nanowire kinking superstructures.
• To elucidate the interplay between defect propagation and surface chemistry during kinking events.
• To establish a general approach for rationally engineering kinking superstructures.

Main Methods:

• High-resolution electron microscopy (HREM) was employed to analyze the structural aspects of kinking.
• Operando infrared spectroscopy was utilized to probe surface chemistry during the synthesis process.
• The study focused on silicon (Si) nanowires undergoing ⟨211⟩ → ⟨111⟩ and ⟨211⟩ → ⟨211⟩ kinking.

Main Results:

• Adsorbed hydrogen atoms were identified as the key factor in selecting ⟨211⟩-oriented growth.
• A continuous twin boundary was found to impart structural coherence, particularly at ⟨211⟩ → ⟨211⟩ kinks.
• The presence of the twin boundary reduces the symmetry of the trijunction, limiting available growth directions.

Conclusions:

• The findings provide critical insights into the role of surface chemical bonding in vapor-liquid-solid (VLS) synthesis.
• A general strategy for the rational engineering of kinking superstructures in nanowires is proposed.
• This work advances the understanding and control of complex nanowire architectures.