High performance electron blocking layer-free InGaN/GaN nanowire white-light-emitting diodes

Area of Science:

• Materials Science
• Solid State Physics
• Optoelectronics

Background:

• Electron overflow is a major cause of efficiency degradation in InGaN/GaN-based white LEDs.
• Traditional AlGaN electron blocking layers can impede hole injection and device performance.

Purpose of the Study:

• To investigate the use of coupled quantum wells to mitigate electron overflow in InGaN/GaN dot-in-a-wire white LEDs.
• To enhance light output power, external quantum efficiency (EQE), and reduce efficiency droop.

Main Methods:

• Incorporation of a specific InGaN quantum well between n-GaN and the active region.
• Integration of a blue-emitting InGaN quantum well between the quantum dot active region and p-GaN.
• Optimization of InGaN quantum well thickness and bandgap energy for electron transport control.

Main Results:

• Significant reduction in electron overflow through the near-surface GaN region.
• Increased light output power and EQE compared to devices without coupled quantum wells.
• High internal quantum efficiency of 58.5% with stable emission and minimal efficiency droop.

Conclusions:

• Coupled quantum wells effectively reduce electron overflow and improve white LED performance.
• The InGaN quantum well structure offers a viable alternative to AlGaN electron blocking layers.
• This approach leads to highly efficient and stable phosphor-free white LEDs.