High-performance triangular miniaturized-LEDs for high current and power density applications

• Main Authors: Lu, Shunpeng, Zhang, Yiping, Zhang, Zi-Hui, Zhu, Binbin, Zheng, Haiyang, Tan, Swee Tiam, Demir, Hilmi Volkan
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Electrical and electronic engineering; GaN Light Emitting Diodes; Thickness
• Online Access: https://hdl.handle.net/10356/152563
• Institution: Nanyang Technological University

This work proposes an effective electrode length model and reveals for the first time the relationship between this model and the mesa shape effect. On the basis of this model, we demonstrate high-performance triangular miniaturized-LEDs (mini-LEDs) and benchmark to the conventional square, and circular shapes of the same mesa area. Here, we systematically study the impact of shaping in mini-LEDs both theoretically and experimentally, which is fundamentally different than that of the conventional regular-sized LEDs. We find that, at the current level of 200 mA, the triangular mini-LEDs deliver an enhancement of 36.4% in the optical output power and a decrease of 9.6% for the forward voltage compared to the commonly used square ones, and also an enhancement of 24.6% in the optical output power and a decrease of 14.3% for the forward voltage compared to the circular ones. The superior optical performance is proved to result from longer effective n-electrode length in the case of the triangular mini-LEDs, which suppresses the self-heating effect and thus well preserves the internal quantum efficiency, whereas the light extraction efficiency and the heat dissipation for the triangular shape are not significantly increased for such small mesa sizes, unlike conventional broad-area LEDs. Meanwhile, the reduced voltage is revealed to stem from the decreased n-GaN resistance. Different than conventional LEDs, these findings therefore indicate that the effective n-electrode length matters substantially for the miniaturized-LEDs.