Failure Mechanism for GaN-Based High-Voltage Light-Emitting Diodes

Chang, Shoou‐Jinn; Chang, Chin Sung; Tseng, Chun-Lung; Shen, C.F.; Chen, Bing-Yang

doi:10.1109/lpt.2014.2314701

Cited by 8 publications

(1 citation statement)

References 13 publications

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“…The HV-LED is defined as a GaN-based LED with series-connection micro-cells, which can be operated at a voltage higher than 20 V and an injection current lower than 100 mA [6][7][8][9][10][11][12]. The design and fabrication of HV-LEDs can eliminate the problem of efficiency droop and maintain the high output power.…”

Section: Introductionmentioning

confidence: 99%

Improved Performance of High-Voltage Vertical GaN LEDs via Modification of Micro-Cell Geometry

Horng

2017

Applied Sciences

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Vertical-type high-voltage light-emitting diodes (HV-LEDs) with 2 × 2 micro-cells were fabricated on Cu substrates, and the micro-cell geometry was modified to enhance the optoelectronic performance. The current spreading in micro-cell is most dominantly affected by the distance between electrode and edge of chip. When square cells were combined in a HV-LED, the device performance was poor due to an obvious current-crowding phenomenon that occurred near the electrodes. This was attributed that the electrodes in these four square micro-cells were all far away from the edges, resulting in the severe current-crowding phenomenon. On the contrary, as the HV-LED was prepared with four rectangle, triangle, or L-shaped micro-cells, the electrodes were close to the edges of micro-cells and the current spreading effect can be easily improved. Although a HV-LED connected with L-shaped cells possessed a better current spreading effect and a lower surface temperature, the light extraction was relatively low because of an electrode-shading loss effect. When triangular cells were used to prepare the HV-LED, the device achieved a superior optoelectronic performance compared with that of other cells because of a lower current-crowding effect and a more uniform light emission. After an epoxy package process, a lower forward voltage of 14.9 V and a higher output power of 353.2 mW were obtained using this HV-LED at an injection current of 80 mA. Additionally, the wall-plug efficiencies of this device at 20 and 80 mA were 41.1% and 29.7%, respectively. The results confirm that the design of triangular cell is beneficial for enhancing the optoelectronic performance of HV-LEDs. Furthermore, the fabrication processes of vertical LEDs have high potential for HV-LED applications.

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