High efficiency of III-nitride micro-light-emitting diodes by sidewall passivation using atomic layer deposition

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• Micro-sized light-emitting diodes (µLEDs) are crucial for advanced display and lighting technologies.
• Effective sidewall passivation is essential to mitigate performance degradation in µLEDs due to surface defects.

Purpose of the Study:

• To investigate the optoelectronic effects of atomic-layer deposition (ALD) for sidewall passivation on µLEDs.
• To compare ALD with conventional plasma-enhanced chemical vapor deposition (PECVD) for µLED sidewall treatment.
• To demonstrate the impact of sidewall passivation on µLED performance metrics like leakage current and external quantum efficiency (EQE).

Main Methods:

• Fabrication and characterization of µLEDs with ALD and PECVD sidewall passivation.
• Comparative analysis of optical emission uniformity and electrical leakage current.
• Measurement of peak external quantum efficiency (EQE) for different µLED sizes.

Main Results:

• ALD passivation resulted in uniform light emission and the lowest leakage current across various µLED sizes.
• µLEDs with ALD sidewall passivation achieved higher peak EQEs (33% for 20 × 20 µm² devices) compared to those without passivation (24%).
• ALD treatment effectively minimized the negative impact of µLED size on peak EQE.

Conclusions:

• ALD is a superior method for µLED sidewall passivation compared to PECVD.
• Proper sidewall treatment using ALD is critical for achieving high-performance and scalable µLEDs.
• ALD passivation enables the development of highly efficient µLEDs with minimized size-dependent efficiency variations.