Investigation of Light Extraction Efficiency in AlGaN Deep-Ultraviolet Light-Emitting Diodes

Light extraction efficiency (LEE) in AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) is investigated using finite-difference time-domain simulations. For flip-chip and vertical LED structures, LEE is obtained to be ${<}10$% due to strong DUV light absorption in the p-GaN layer. In flip-...

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Bibliographic Details
Published inApplied physics express Vol. 6; no. 6; pp. 062101 - 062101-4
Main Authors Ryu, Han-Youl, Choi, Il-Gyun, Choi, Hyo-Sik, Shim, Jong-In
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.06.2013
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Summary:Light extraction efficiency (LEE) in AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) is investigated using finite-difference time-domain simulations. For flip-chip and vertical LED structures, LEE is obtained to be ${<}10$% due to strong DUV light absorption in the p-GaN layer. In flip-chip LEDs, LEE of transverse-magnetic (TM) modes is found to be more than ten times smaller than that of transverse-electric (TE) modes, which explains the decreasing behavior of external quantum efficiency of DUV LEDs with decreasing wavelength. It is also found that vertical LED structures can have advantages over flip-chip structures for increasing LEE in the TM mode.
Bibliography:Schematic side-view diagram of FDTD computational domains of UV LED structures. (a) FC LED structure. (b) Vertical LED structure. Electric field intensity distribution of light emitted from the dipole source. (a) TE mode. (b) TM mode. Simulated results of LEE for the FC LED structure shown in Fig. (a). LEEs of the TE and TM modes are plotted as a function of the thickness of the p-GaN layer. Simulated results of LEE for the vertical LED structure shown in Fig. (b). LEEs of the TE and TM mode are plotted as a function of the thickness of the p-GaN layer.
ISSN:1882-0778
1882-0786
DOI:10.7567/APEX.6.062101