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Suigen, South Korea

Ryu H.-Y.,Inha University | Shim J.-I.,Hanyang University | Kim C.-H.,EpiValley Co. | Choi J.H.,EpiValley Co. | And 4 more authors.
IEEE Photonics Technology Letters | Year: 2011

The authors investigate efficiency and electron leakage characteristics in GaN-based light-emitting diodes (LEDs) without AlGaN electron-blocking-layer (EBL) structures. Both simulation and electroluminescence (EL) measurement results show that the internal quantum efficiency decreases rapidly as the thickness of an undoped GaN interlayer between active layers and a p-GaN layer increases, which is caused by electron leakage from active layers to the p-GaN due to inefficient hole injection. However, photoluminescence (PL) measurement results show that the quality of active layers deteriorates as the interlayer thickness decreases. The EL and PL results imply that the optimization of the undoped GaN interlayer thickness is important for achieving high internal quantum efficiency in AlGaN-EBL-free LEDs. © 2011 IEEE. Source


Patent
Epivalley Co. | Date: 2010-08-02

The present disclosure provides a dimming control method for a display having a light-emitting device which includes: a first light-emitting body including an active layer generating a first light by recombination of electrons and holes; and a second light-emitting body excited by the first light and emitting a second light having a longer wavelength than the first light, the dimming control method including: controlling the power which will be supplied to the light-emitting device according to a dimming request; and adjusting the brightness of the display according to the controlled power using the second light-emitting body containing a first fluorescent material having a characteristic that chromaticity coordinates are shifted in a first direction according to the power control and a second fluorescent material having a characteristic that chromaticity coordinates are shifted in a second direction opposite to the first direction according to the power control.

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