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Tuning the Liquid-Vapour Interface of VLS Epitaxy for Creating Novel Semiconductor Nanostructures
Galih R Suwito1, Vladimir G Dubrovskii2, Zixiao Zhang3
1Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 0C5, Canada.
Nanomaterials (Basel, Switzerland)
|March 11, 2023
Summary
Controlling semiconductor nanostructure shape is key for applications. This study shows that changing the micro-crucible opening size precisely controls the morphology and composition of silicon-germanium nanostructures via vapour-liquid-solid growth.
Area of Science:
- Materials Science
- Nanotechnology
- Semiconductor Physics
Background:
- Controlling semiconductor nano- and micro-structure morphology and composition is vital for scientific research and technological applications.
- Silicon-germanium (Si-Ge) nanostructures are important materials with tunable electronic and optical properties.
Purpose of the Study:
- To investigate the influence of micro-crucible geometry on the fabrication of Si-Ge semiconductor nanostructures.
- To understand the vapor-liquid-solid (VLS) nucleation and growth mechanisms dependent on the liquid-vapor interface area.
- To demonstrate a method for tuning nanostructure morphology and composition by controlling geometric parameters.
Main Methods:
- Fabrication of Si-Ge nanostructures using photolithographically defined micro-crucibles on Si substrates.
- Chemical Vapor Deposition (CVD) of Germanium (Ge) with controlled liquid-vapor interface sizes.
- Transmission Electron Microscopy (TEM) for structural and compositional analysis.
Main Results:
- Nanostructure morphology and composition strongly depend on the micro-crucible opening size (liquid-vapor interface area).
- Ge crystallites nucleated in larger openings (3.74-4.73 μm²) but not in smaller ones (1.15 μm²).
- Different nanostructures formed: lateral nano-trees in smaller openings and nano-rods in larger openings, both epitaxially related to the Si substrate.
Conclusions:
- The size of the liquid-vapor interface in micro-crucibles dictates the nucleation and growth of Si-Ge nanostructures via VLS mechanism.
- A model shows incubation time for VLS nucleation is inversely proportional to the opening size.
- Geometric control of the liquid-vapor interface offers a precise method for tuning the morphology and composition of semiconductor nanostructures.
