Improved light extraction from large-area vertical light-emitting diodes with deep hole-patterns using nanosphere...

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Light extraction efficiency is a critical parameter for vertical light emitting diodes (VLEDs).
• Existing VLED designs often face limitations in maximizing light output due to internal reflection and absorption.

Purpose of the Study:

• To develop and evaluate an improved light extraction method for large-area VLEDs.
• To investigate the impact of deep hole patterns fabricated via nanosphere lithography on VLED performance.

Main Methods:

• Fabrication of ordered deep-hole patterns on n-type Gallium Nitride (GaN) surfaces using nanosphere lithography.
• Utilized a 150 nm Nickel (Ni) dot mask for deep etching of periodic hole patterns (360 nm diameter, 1.0 and 1.5 µm depths).
• Compared light output power of patterned VLEDs against a reference VLED without patterns.

Main Results:

• VLEDs with 1.0 µm and 1.5 µm deep hole patterns exhibited 4.13x and 4.86x higher light output power, respectively, compared to the reference.
• Enhancements attributed to light scattering from hole sidewalls and increased surface area for light emission.
• Potential reduction in photon reabsorption within the n-GaN layer for deeper patterns.

Conclusions:

• Deep hole patterns fabricated using nanosphere lithography significantly improve light extraction efficiency in VLEDs.
• The proposed method offers a viable strategy for enhancing the performance of large-area VLEDs.
• Further investigation into photon reabsorption effects could optimize future VLED designs.