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ABSTRACT: In this study, the fabrication and characterization of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with further improvement by the design of a reflective current blocking layer (CBL) were described, and these are demonstrated to be an inexpensive and feasible way for improving the performance of LEDs. With the reflective CBL, not only was the injected current forced to spread outside instead of flowing directly downward under a p-pad, but the light generated from the active region could also be extracted outside of the LED by reflection under the p-pad. At 20 mA, as compared to the conventional LED, the light output power of the LEDs with the normal and reflective CBL can be increased by 15.7% and 25.8%, respectively. We found that the forward voltages of the LEDs with CBL structure were both about 3.7 V at 20 mA, which was slightly higher than that of the conventional LED (3.6 V). In our experiment, the further increase in the light output power of the reflective CBL LED could be attributed to more current injection into the light-emitting active region outside of the p-pad by the CBL and a reduction in optical absorption at the p-pad with more extraction by the reflective design.
Semiconductor Science and Technology 07/2011; 26(9):095013. · 1.72 Impact Factor
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ABSTRACT: In this report, the motivation of why we attempt to design current spreading, or current surrounding, is try to provide other current paths, expect to improve the current spreading of LEDs and get lower forward voltage at the same time. Attempt to avoid the trade-off between p -electrode area for uniform current spreading and emitting area for light output of LEDs.Compared to reference LEDs, we can find that the light output intensity of chips with n -pad current surrounding design will decay at higher current injection. This can be attributed to the metal on pitch we design, with better current spreading and much metal area connected to n -pad, so less current crowding effect and less heat-accumulation in chips (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
physica status solidi (c) 04/2010; 7(7‐8):2187 - 2189.
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ABSTRACT: In this study, the fabrication and characterization of InGaN-GaN multiple-quantum-well light-emitting diodes (LEDs) with silicon dioxide (SiO<sub>2</sub>) nanoparticles as the current-blocking layer (CBL) are described. The performance was improved by introducing SiO<sub>2</sub> nanoparticles, not deposited by commonly used plasma-enhanced chemical vapor deposition, as the CBL beneath the p-pad. The injected current was forced to spread outside instead of flowing directly downward. At 20 mA, the light output power of the LED with a CBL was increased 15.7% as compared to that of the conventional LED. The forward voltage of the LED with the SiO<sub>2</sub> nanoparticle CBL was 3.34 V at 20 mA, which was slightly higher than that of the conventional LED (3.29 V). The increase in the light output power can be attributed to the injection of additional current into the light-emitting active layer of the LED by the SiO<sub>2</sub> nanoparticles CBL and thus a reduction in optical absorption at the p-pad.
IEEE Photonics Technology Letters 08/2009; · 2.19 Impact Factor
