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Surface Hydrogen Enables Subeutectic Vapor-Liquid-Solid Semiconductor Nanowire Growth
Saujan V Sivaram1, Ho Yee Hui1, María de la Mata2
1School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
Nano Letters
|June 28, 2016
Summary
Hydrogen atoms on germanium (Ge) nanowire sidewalls enable supercooling of gold-germanium (AuGe) catalysts, controlling nanowire growth below the eutectic temperature. This discovery highlights the crucial role of sidewall chemistry in catalyst behavior.
Area of Science:
- Materials Science
- Nanotechnology
- Chemical Engineering
Background:
- Vapor-liquid-solid (VLS) nanowire growth typically occurs above the bulk eutectic temperature.
- The mechanisms enabling subeutectic VLS growth, where nanowires form below this temperature, are not fully understood.
- Controlling catalyst behavior is key to understanding and optimizing nanowire synthesis.
Purpose of the Study:
- To investigate the fundamental processes governing subeutectic nanowire growth.
- To elucidate the role of sidewall chemistry in catalyst supercooling and transport.
- To identify methods for regulating catalyst composition during nanowire synthesis.
Main Methods:
- In situ infrared spectroscopy to quantify hydrogen atom coverage on Ge nanowire sidewalls.
- A "regrowth" step followed by ex situ electron microscopy to determine catalyst phase.
- Controlled delivery of hydrogen radicals to the catalyst.
Main Results:
- Adsorption of hydrogen atoms on Ge nanowire sidewalls enables supercooling of the AuGe catalyst.
- Hydrogen radicals alone can maintain a supercooled catalyst state.
- Sidewall chemistry significantly influences the catalyst's state and composition.
Conclusions:
- Sidewall chemistry is central to achieving supercooled catalysts in nanowire growth.
- This work introduces new methods for regulating catalyst composition.
- The findings provide strategies for subeutectic nanowire growth in various material systems.
