Identification of multi-color emission from coaxial GaInN/GaN multiple-quantum-shell nanowire LEDs

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Nanostructures

Background:

• Coaxial gallium indium nitride/gallium nitride (GaInN/GaN) multiple-quantum-shell (MQS) nanowires are promising for light-emitting diodes (LEDs).
• Achieving multi-color emission and controlling wavelength are key challenges in MQS nanowire LED development.

Purpose of the Study:

• To investigate multi-color electroluminescence (EL) from coaxial GaInN/GaN MQS nanowire LEDs.
• To understand the relationship between crystal plane orientation and emission characteristics.
• To optimize growth conditions for improved crystalline quality and wavelength control.

Main Methods:

• Selective growth of MQS nanowire samples on patterned GaN/sapphire substrates via metal-organic chemical vapor deposition (MOCVD).
• Fabrication of nanowire-based LEDs.
• Electroluminescence (EL) and photoluminescence (PL) spectroscopy to analyze emission properties.

Main Results:

• Observed three distinct EL emission peaks at 440 nm, 540 nm, and 630 nm, attributed to nonpolar, semipolar, and polar crystal facets.
• Demonstrated wavelength shifting from 430 nm to 520 nm by inserting AlGaN spacers, suppressing indium decomposition.
• Verified non-polarization of emission and identified yellow-red emission sources related to indium fluctuations and defects.

Conclusions:

• Multi-color emission is achievable from coaxial GaInN/GaN MQS nanowires due to different crystal facets.
• AlGaN spacer insertion effectively tunes emission wavelength and improves crystalline quality.
• Optimizing MQS nanowire growth, particularly for polar c-planes, is crucial for high-efficiency nanowire-based micro-LEDs and white LEDs.