Electron mobilities approaching bulk limits in "surface-free" GaAs nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Achieving bulk-like charge carrier mobilities in semiconductor nanowires is crucial for advanced electronic devices.
• Surface states and defects in nanowires limit carrier transport and device performance.

Purpose of the Study:

• To investigate the impact of aluminum gallium arsenide (AlGaAs) shell coating on gallium arsenide (GaAs) nanowire carrier properties.
• To enhance carrier mobility and lifetime in GaAs nanowires for improved electronic applications.

Main Methods:

• Fabrication of GaAs/AlGaAs core-shell nanowires.
• Utilizing optical pump-terahertz probe spectroscopy to measure carrier transport dynamics.
• Analyzing carrier lifetimes and mobilities as a function of AlGaAs shell thickness.

Main Results:

• Carrier lifetimes and mobilities in GaAs nanowires significantly improved with increasing AlGaAs shell thickness.
• Optimized GaAs/AlGaAs core-shell nanowires achieved electron mobilities up to 3000 cm(2) V(-1) s(-1), over 65% of bulk GaAs values.
• Photoconductivity lifetime reached 1.6 ns, indicating effective elimination of surface states.

Conclusions:

• Engineering GaAs nanowire surfaces with AlGaAs shells is an effective strategy for high carrier mobility and lifetime.
• The high interface quality and reduced defects in core-shell structures approach bulk semiconductor performance.
• This approach holds promise for developing high-performance nanowire-based electronic devices.