High efficiency GaN-based light emitting diode with nano-patterned ZnO surface fabricated by wet process

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Gallium Nitride (GaN)-based light-emitting diodes (LEDs) are crucial for efficient lighting.
• Improving optical output power and light extraction efficiency remains a key challenge in LED development.

Purpose of the Study:

• To enhance the optical output power of GaN-based LEDs.
• To investigate a novel bi-layer transparent top electrode scheme for improved light extraction.

Main Methods:

• Fabrication of a bi-layer transparent electrode comprising Ga-doped ZnO (GZO) with nano-patterns and a p-type Indium Tin Oxide (ITO) layer.
• Utilizing a wet etching process to create nano-patterns on the GZO layer.
• Optimizing wet-etching conditions (e.g., HCl concentration and duration) to maximize light extraction efficiency.

Main Results:

• Nano-pattern formation and optoelectronic properties were found to be dependent on etching duration.
• The underlying ITO layer ensured unaffected current spreading despite the nano-patterned GZO surface.
• A 43.1% enhancement in optical output power was achieved at 100 mA injection current for LEDs with nano-patterns etched using 0.025% HCl for 30 seconds.
• No significant degradation in electrical properties was observed compared to reference LEDs.

Conclusions:

• The proposed bi-layer transparent top electrode scheme effectively enhances the optical output power of GaN-based LEDs.
• Wet etching is a viable method for creating nano-patterns that improve light extraction efficiency without compromising electrical performance.
• This approach offers a promising strategy for developing high-performance GaN-based LEDs.