Visualizing highly localized luminescence in GaN/AlN heterostructures in nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Gallium nitride (GaN) and aluminum nitride (AlN) heterostructures are crucial for optoelectronic devices.
• Understanding nanoscale optical properties is essential for optimizing device performance.

Purpose of the Study:

• To investigate the optical properties of GaN/AlN quantum discs (QDiscs) within GaN nanowires.
• To characterize unintentional lateral inclusions, identified as quantum rods (QRods).

Main Methods:

• Spatially resolved nanoscale cathodoluminescence (nanoCL) spectroscopy.
• Scanning transmission electron microscopy (STEM) in spectrum imaging mode.
• STEM dark-field imaging.

Main Results:

• Highly localized luminescence (down to 5 nm) from QDiscs due to GaN/AlN band gap differences.
• Identification and optical activity confirmation of unintentional QRods grown on nanowire sidewalls.
• QRods exhibit emission at similar, often shorter, wavelengths compared to QDiscs.

Conclusions:

• NanoCL is effective for discriminating emission from individual QDiscs and identifying lateral nanostructures.
• Unintentional QRods are optically active and influence the overall emission characteristics.
• Precise nanoscale optical characterization is vital for understanding and controlling GaN-based nanostructures.