Abstract
Based on the proposed experimental method, the current spreading length of GaN-based light-emitting diodes (LEDs) was measured and analyzed for practical device design. In this study, Thompson's and Guo's models, which are categorized according to vertical series resistance (in particular, p-type contact resistance), were used to extract device parameters. It was shown that the measured current spreading length strongly depends on the injected current density. For LEDs fabricated with low-resistance p-type contacts, this behavior could be explained in terms of the accelerated current crowding with higher current densities occurring as a result of the reduced voltage drop across the junction, which is in good agreement with Thompson's relation. However, for LEDs fabricated with high-resistance p-contacts, unlike Guo's prediction, the measured current spreading length also showed a strong dependence on the injected current density. This was attributed to thermal heating at the p-contact, resulting in the reduction of the voltage drop across the p-contact and so junction voltage, which is also in agreement with Thompson's model. Based on the measured parameters and the design rule, efficient p-type reflectors, namely, hybrid reflectors were designed. Compared with conventional ones, LEDs fabricated with the hybrid reflectors exhibited better output power at a reasonable forward voltage, indicating that the proposed method is effective in understanding the actual current spreading and hence the practical design of high-efficiency LEDs.
Original language | English |
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Pages (from-to) | 625-632 |
Number of pages | 8 |
Journal | IEEE Journal of Quantum Electronics |
Volume | 43 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2007 Aug |
Keywords
- Current crowding
- Design
- GaN
- Light-emitting diode (LED)
- Reflector
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering