Band-gap modulation in single-crystalline Si1-xGex nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Silicon-germanium (Si1-xGex) alloys are crucial for advanced electronic and optoelectronic devices.
• Controlling the band-gap of semiconductor nanowires is key for tunable photonic applications.

Purpose of the Study:

• To demonstrate the tunable energy band-gap of single-crystalline Si1-xGex nanowires.
• To explore the modulation of band-gap through alloy composition and nanowire diameter.
• To highlight implications for group-IV semiconductor nanowire photonics.

Main Methods:

• Synthesis of single-crystalline Si1-xGex nanowires using Au catalyst-assisted chemical vapor deposition.
• Precise control over Si and Ge composition (0 <= x <= 1) by managing precursor decomposition kinetics.
• Optical band-edge absorption measurements to determine energy band-gap.

Main Results:

• Achieved reproducible control over the Si1-xGex alloy composition across the entire composition range.
• Demonstrated energy band-gap tuning from 0.68 eV to 2.25 eV, covering NIR to visible regions.
• Observed band-gap shifts correlated with increasing Ge content and decreasing nanowire diameter.

Conclusions:

• The energy band-gap of Si1-xGex nanowires can be effectively modulated over a broad spectral range.
• Alloying and diameter control offer a pathway for designing nanowires for specific photonic functionalities.
• Findings suggest significant potential for Si1-xGex nanowires in next-generation group-IV photonics.