標題: | Improved Performance of High-Voltage Vertical GaN LEDs via Modification of Micro-Cell Geometry |
作者: | Wu, Ping-Chen Ou, Sin-Liang Horng, Ray-Hua Wuu, Dong-Sing 電子工程學系及電子研究所 Department of Electronics Engineering and Institute of Electronics |
關鍵字: | vertical light emitting diodes;high-voltage light emitting diodes;micro-cell geometry;current crowding effect;spatial distribution image |
公開日期: | 1-六月-2017 |
摘要: | Vertical-type high-voltage light-emitting diodes (HV-LEDs) with 2 x 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. |
URI: | http://dx.doi.org/10.3390/app7060506 http://hdl.handle.net/11536/145730 |
ISSN: | 2076-3417 |
DOI: | 10.3390/app7060506 |
期刊: | APPLIED SCIENCES-BASEL |
Volume: | 7 |
Issue: | 6 |
起始頁: | 0 |
結束頁: | 0 |
顯示於類別: | 期刊論文 |