Investigation of Step-Stress Accelerated Degradation Test Strategy for Ultraviolet Light Emitting Diodes

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Devices

Background:

• III-nitride-based ultraviolet light emitting diodes (UV LEDs) offer diverse applications in purification, photolithography, and medical treatments.
• Uncertainty in UV LED reliability and failure mechanisms hinders widespread adoption.
• Developing effective reliability testing is essential for advancing UV LED technology.

Purpose of the Study:

• To compare three step-stress accelerated degradation test (SSADT) plans for UV LEDs.
• To identify the most effective SSADT strategy for determining UV LED reliability.
• To understand the influence of different stress factors on UV LED failure mechanisms.

Main Methods:

• Three SSADT plans were evaluated using stepwise increasing temperature and driving current loads.
• The impact of driving current and temperature on UV LED failure modes was analyzed.
• Comparative analysis of failure mechanisms across different SSADT conditions was performed.

Main Results:

• Failure mechanisms varied significantly across different SSADT conditions.
• Driving current was identified as a more sensitive factor influencing UV LED failure mechanisms than temperature.
• The stepped temperature accelerated degradation test demonstrated effectiveness.

Conclusions:

• The stepped temperature accelerated degradation test, with carefully selected current levels, is recommended for UV LED reliability assessment.
• Understanding the role of driving current in failure mechanisms is key for accurate UV LED reliability testing.
• Optimized reliability testing will accelerate the deployment of UV LEDs in critical applications.