Simple Approach to Mitigate the Emission Wavelength Instability of III-Nitride μLED Arrays

Area of Science:

• Optoelectronics
• Semiconductor Physics
• Materials Science

Background:

• III-nitride semiconductors possess intrinsic polarization due to their wurtzite structure, influencing optoelectronic properties.
• Polarization-induced quantum-confined Stark effect causes emission wavelength shifts in visible LEDs, hindering full-color display fabrication.
• Color instability in microdisplays (AR/VR) is a significant challenge due to human eye sensitivity to color variations.

Purpose of the Study:

• To demonstrate an approach for stabilizing the emission wavelength of III-nitride microLEDs.
• To address the color instability issue in III-nitride visible LEDs for microdisplay applications.
• To provide a solution for the long-standing challenge in III-nitride optoelectronics.

Main Methods:

• Epitaxial integration of green microLEDs with a microcavity.
• Coupling microLED emission with the microcavity's optical mode.
• Comparative analysis of microLEDs with and without microcavity integration under varying injection currents.

Main Results:

• MicroLEDs integrated with microcavities exhibited negligible emission wavelength shift with increasing injection current.
• Identical microLEDs without microcavities showed a significant wavelength shift from 560 nm to 510 nm under identical conditions.
• Demonstrated a method to maintain stable color output essential for high-resolution displays.

Conclusions:

• The integration of microLEDs and microcavities effectively suppresses the emission wavelength shift caused by intrinsic polarization.
• This approach offers a practical solution to the color instability problem in III-nitride visible LEDs.
• The developed technique is a significant advancement for fabricating stable, full-color microdisplays for AR/VR applications.