Jpn. J. Appl. Phys. 43 (2004) pp. 5809-5813 |Previous Article| |Next Article| |Table of Contents|
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High-Extraction-Efficiency Blue Light-Emitting Diode Using Extended-Pitch Photonic Crystal
Semiconductor Device Research Center, Semiconductor Company, Matsushita Electric Industrial Co., Ltd., 1-1 Saiwai-cho, Takatsuki, Osaka 569-1193, Japan
(Received January 15, 2004; accepted January 26, 2004; published August 25, 2004)
We have integrated the surface photonic crystal (PhC) on GaN-based blue light-emitting diodes (LEDs) for the first time in order to enhance the extraction efficiency of the LEDs. With the finite-difference time-domain method, we have calculated 3.6-fold enhancement in light output. The theoretical calculations have revealed that the optimum pitch of the PhC is much longer than the emission wavelength when the distance between the PhC and the active layer of LEDs is short. This design enables PhC formation on chemically stable GaN surfaces. In addition, an indium tin oxide (ITO)-based transparent electrode is formed directly on the surface of PhC to realize light emission from the whole area of the LED. The fabricated PhCs have increased the light output of blue LEDs by 1.5 times compared with the LEDs without PhC. We have demonstrated that PhC will realize highly efficient solid-state lighting with GaN-based LEDs.
KEYWORDS:photonic crystal, GaN, LED, extraction efficiency, finite-difference time-domain method
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