Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded...

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Physics

Background:

• Conventional AlGaN deep UV LEDs use electron blocking layers (EBLs) to prevent electron leakage.
• EBLs can lead to hole depletion and reduced hole injection efficiency due to polarization charges.
• Electron leakage and efficiency droop remain significant challenges in deep UV AlGaN LEDs.

Purpose of the Study:

• To propose and investigate an electron blocking layer-free (EBL-free) AlGaN deep UV LED structure.
• To enhance electron confinement and hole injection efficiency.
• To improve the internal quantum efficiency and reduce efficiency droop.

Main Methods:

• Utilizing graded staircase quantum barriers (GSQBs) instead of conventional quantum barriers (QBs).
• Simulating and analyzing electron transport, thermal velocity, and mean free path in the active region.
• Evaluating the overlap of electron and hole wavefunctions and the quantum-confined Stark effect.

Main Results:

• The GSQB structure significantly reduces electron leakage into the p-region.
• Electron and hole wavefunction overlap is improved, reducing the quantum-confined Stark effect.
• Internal quantum efficiency and output power are approximately 2.13 times higher than conventional structures at 60 mA.
• Efficiency droop is reduced to ~20.68% (0-60 mA), substantially lower than conventional designs.

Conclusions:

• The proposed EBL-free structure with GSQBs effectively confines electrons and enhances hole injection.
• GSQBs offer a promising approach to overcome the limitations of conventional EBLs in deep UV AlGaN LEDs.
• This design leads to superior performance, including higher efficiency and reduced droop, paving the way for advanced deep UV optoelectronic devices.