In the rapidly evolving world of micro-light-emitting diodes (μLEDs), a groundbreaking study has emerged from the labs of National Yang Ming Chiao Tung University in Taiwan. Led by Tsung-Chih Wan of the Institute of Electronics, this research delves into the intricate effects of chip size and surface treatment on the performance of thin-film blue-light μLEDs. The findings, published in Applied Surface Science Advances, could significantly impact the energy sector by enhancing the efficiency and longevity of μLED-based technologies.
The study focuses on two key aspects: the size of the μLED chips and the treatment of the N-polar n-GaN surface. Wan and his team fabricated μLEDs in two sizes—10 × 10 μm² and 25 × 25 μm²—and subjected them to different etching times using a potassium hydroxide (KOH) solution. The goal was to understand how these variables affect the performance of the μLEDs, particularly in terms of light output power and external quantum efficiency (EQE).
One of the most striking findings is the impact of surface roughening on light output power. “Regardless of the treatments, all samples exhibit similar forward bias characteristics,” Wan explains. However, the light output power increased significantly after the n-GaN surface was roughened. This suggests that surface treatment could be a crucial factor in optimizing μLED performance.
The study also revealed that the 10 μm μLEDs showed higher EQE before the laser lift-off (LLO) process, with the implanted μLEDs exhibiting the lowest EQE. However, after optimal 4-minute etching, the EQE of the 10 μm and 25 μm μLEDs became almost identical. The implanted μLEDs, while still slightly lower, showed a remarkable 74% improvement in EQE. This indicates that the size and etching time of the μLEDs play a pivotal role in their efficiency.
The research also explored the photoluminescence (PL) decay and ideality factor of the μLEDs. The 10 μm μLEDs demonstrated the shortest PL decay, while the 25 μm μLEDs had the longest. The ideality factor, which measures the quality of the p-n junction, was highest in the 10 μm μLEDs and lowest in the As+ ion-implanted μLEDs. These findings provide valuable insights into the size and etching time dependence of the EQE characteristics of μLEDs.
So, what does this mean for the future of μLED technology? The implications are vast, particularly for the energy sector. μLEDs are already being explored for use in high-efficiency lighting, displays, and even solar energy harvesting. By optimizing the size and surface treatment of μLEDs, researchers can enhance their efficiency, longevity, and overall performance. This could lead to more energy-efficient devices, reduced power consumption, and lower operational costs.
Wan’s research, published in Applied Surface Science Advances, which translates to “Advances in Surface Science and Applied Technology,” is a significant step forward in the field of μLED technology. As the demand for energy-efficient solutions continues to grow, studies like this will be instrumental in shaping the future of the energy sector. The insights gained from this research could pave the way for the development of next-generation μLEDs that are not only more efficient but also more sustainable.