Hexagonal silicon grown from higher order silanes.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Growth

Background:

• Epitaxial growth of hexagonal silicon (Si) shells on semiconductor nanowires is crucial for advanced electronic and optoelectronic devices.
• Previous research primarily utilized disilane (Si2H6) as a silicon precursor, with limitations in growth rate and control.

Purpose of the Study:

• To explore tetrasilane (Si4H10) as a superior precursor for epitaxially growing defect-free hexagonal silicon shells.
• To investigate and compare the growth kinetics and mechanisms of silicon shells using tetrasilane versus disilane.
• To achieve non-tapered silicon shells with enhanced growth rates at lower temperatures.

Main Methods:

• Epitaxial growth of hexagonal silicon shells on wurtzite gallium phosphide (GaP) nanowires.
• Utilized two silicon precursors: tetrasilane (Si4H10) and disilane (Si2H6).
• Analyzed growth kinetics across two temperature regimes (415 °C-600 °C and 600 °C-735 °C) and determined activation energies.

Main Results:

• Identified two distinct surface reaction mechanisms (adsorbate interaction and chemisorption) for both precursors at different temperatures.
• Tetrasilane exhibited a lower activation energy (1.5 ± 0.1 eV) compared to disilane (2.4 ± 0.2 eV) in the low-temperature regime.
• Achieved non-tapered silicon shells with over 50 times higher growth rates below 460 °C using tetrasilane, significantly reducing inverse tapering observed with disilane.

Conclusions:

• Tetrasilane (Si4H10) is a highly effective precursor for growing high-quality, defect-free hexagonal silicon shells.
• The use of tetrasilane allows for significantly faster growth rates and improved shell morphology at lower temperatures.
• This advancement in silicon shell growth using tetrasilane holds promise for reduced impurity incorporation and enhanced device performance.