TY - JOUR
T1 - Increased light extraction from vertical GaN light-emitting diodes with ordered, cone-shaped deep-pillar nanostructures
AU - An, Ho Myoung
AU - Sim, Jae In
AU - Shin, Ki Seob
AU - Sung, Yun Mo
AU - Kim, Tae Geun
N1 - Funding Information:
Manuscript received January 5, 2012; revised February 21, 2012; accepted March 6, 2012. Date of current version May 8, 2012. This work was supported in part by the National Research Foundation of Korea Grant funded by the Korean Government (MEST) under Grant 2011-0028769, the Technology Innovation Program (Industrial Strategic Technology Development Program, 10035430, Development of High Efficiency Light Emitting Diode for Illumination) funded by the Ministry of Knowledge Economy, Korea.
Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012
Y1 - 2012
N2 - In this paper, improved light extraction using cone-shaped deep-pillar nanostructures is demonstrated on the Honeycomb-type vertical GaN light-emitting diodes (VLEDs). In order to produce ordered, cone-shaped deep-pillar patterns on the surface of an n-type GaN, double-layered polystyrene (PS) nanospheres of 500-nm size were coated onto the n-GaN layer by a simple spin-coating. Then, immediately after the O 2 plasma ashing for double-layered PS beads, the Ni metal was deposited and lifted off to form a hard mask for deep pillar etching. Then, the three VLEDsthe reference VLED with no patterns and the two VLEDs with ordered, cone-shaped pillar patterns of 1.0 and 1.5 μ m depth on the n-type GaN surfacewere prepared for comparison. As a result, the output power for the proposed VLEDs with 1.0-and 1.5-μ m-deep cone-shaped patterns has been increased by 200% and 214%, respectively, at 350 mA as compared to the reference VLED. There was a slight sacrifice of operational voltage and leakage current. The improved optical properties are attributed to the multiple scattering of light from the sidewall of the cone-shaped patterns and the increased surface dimension.
AB - In this paper, improved light extraction using cone-shaped deep-pillar nanostructures is demonstrated on the Honeycomb-type vertical GaN light-emitting diodes (VLEDs). In order to produce ordered, cone-shaped deep-pillar patterns on the surface of an n-type GaN, double-layered polystyrene (PS) nanospheres of 500-nm size were coated onto the n-GaN layer by a simple spin-coating. Then, immediately after the O 2 plasma ashing for double-layered PS beads, the Ni metal was deposited and lifted off to form a hard mask for deep pillar etching. Then, the three VLEDsthe reference VLED with no patterns and the two VLEDs with ordered, cone-shaped pillar patterns of 1.0 and 1.5 μ m depth on the n-type GaN surfacewere prepared for comparison. As a result, the output power for the proposed VLEDs with 1.0-and 1.5-μ m-deep cone-shaped patterns has been increased by 200% and 214%, respectively, at 350 mA as compared to the reference VLED. There was a slight sacrifice of operational voltage and leakage current. The improved optical properties are attributed to the multiple scattering of light from the sidewall of the cone-shaped patterns and the increased surface dimension.
KW - Cone-shaped
KW - Double layer coating
KW - Gallium nitride
KW - Honeycomb-type
KW - Nanosphere lithography
KW - Vertical light emitting diode
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U2 - 10.1109/JQE.2012.2190587
DO - 10.1109/JQE.2012.2190587
M3 - Article
AN - SCOPUS:84861147717
SN - 0018-9197
VL - 48
SP - 891
EP - 896
JO - IEEE Journal of Quantum Electronics
JF - IEEE Journal of Quantum Electronics
IS - 7
M1 - 6183454
ER -