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15 February 2008 Recent status of white LEDs and nitride LDs
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We fabricated two types of high luminous efficiency white light emitting diodes (LEDs). The first one is the white LED, which had a high luminous efficiency (ηL) of 161 Lm/W with the high luminous flux (φv) of 9.89 Lm at a forward- current of 20 mA. Used blue LED had a high output power (φe) of 42.2 mW and high external quantum efficiency (ηex) of 75.5%. The second one is the luminous-efficiency-maximized white-LED with a low forward-bias voltage (Vf) of 2.80 V, which is almost equal to the theoretical limit. ηL and wall-plug efficiency (WPE) were 169 Lm/W and 50.8%, respectively, at 20 mA. They were approximately twice higher than those of a tri-phosphor fluorescent lamp (90 Lm/W and 25%). Moreover, we succeeded in fabricating longer wavelength laser diodes (LDs) with an emission wavelength of 488 nm under CW current condition by optimizing the growth conditions and structure of LDs. To our knowledge, this wavelength is the longest for under CW current condition in GaN-based LDs.
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Takashi Miyoshi, Tomoya Yanamoto, Tokuya Kozaki, Shin-ichi Nagahama, Yukio Narukawa, Masahiko Sano, Takao Yamada, and Takashi Mukai "Recent status of white LEDs and nitride LDs", Proc. SPIE 6894, Gallium Nitride Materials and Devices III, 689414 (15 February 2008);


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