Fabrication and Characterization of GaN Light Emitting Diodes with SiO2 Current-Blocking Layer
| Autor: | Che-wei Tung, 董哲惟 |
|---|---|
| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Improving non-uniform current spreading of GaN light emitting diodes (LED) to obtain high light-output efficiency is one of the most important issues in the LED industry. Because sapphire is an insulating substrate, both the p-type and n-type contacts are usually located on the same side of the chip. As a result, the current flows laterally according to the voltage and resistance distribution and tends to crowd around electrodes if no special design is made. In addition, the light generated in the active region beneath the opaque p-pad metal contact is blocked. It reduces the extraction efficiency of the LED. In this research, we made various devices of different processes and structures. The resulted LED’s I-V and L-I curves were measured and compared. We designed a new mask pattern and developed ITO process to obtain a uniform current spreading, and used silicon dioxide as a current-blocking layer(CBL) under the p-pad to increase the light-output power. The resulted L–I curves exhibit two times increase in the output power for LED with ITO layer and 7.5% increase for LED with CBL structure over the conventional diodes at the same bias current, while the associated area ratios in the mask design are 6.84(ITO/p-pad) and 0.11(p-pad/mesa), respectively. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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