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Proceedings Paper

Current spreading and its related issues in GaN-based light emitting diodes
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Paper Abstract

High quality epitaxial growth and uniform current spreading are essential to III-nitride light emitting diodes (LEDs) for superior wall-plug efficiency and reliability. An analysis method of current spreading based on 3-dimensional circuit modeling is introduced. We have investigated influences of the current spreading in the lateral-electrode type blue LEDs of 320 × 320 μm2 size theoretically and experimentally. It is known that the current spreading can be greatly reduced by careful design of electrode pattern. Uniform current spreading is very important to improve electrical and optical characteristics such as series resistance, efficiency droop, leakage current with operational time leakage current, and electrostatic discharge (ESD) voltage. A method improving ESD voltage is presented by inserting floating metal near the n-electrode. About 4 times larger ESD voltages are experimentally measured at LEDs with floating metal compared to conventional LEDs without one. The internal quantum efficiency (IQE) is the most important factor affecting overall LED performances. A measurement method of the IQE measurable just at room temperature is proposed and demonstrated. The method utilizes both the time responses of the time-resolved photoluminescence (TRPL) as a function of the excitation femtosecond laser pumping power and their theoretical analysis based on the carrier rate equation.

Paper Details

Date Published: 16 February 2009
PDF: 9 pages
Proc. SPIE 7216, Gallium Nitride Materials and Devices IV, 72160V (16 February 2009); doi: 10.1117/12.808393
Show Author Affiliations
Jong-In Shim, Hanyang Univ. (Korea, Republic of)
Joosun Yun, Hanyang Univ. (Korea, Republic of)
Hyunsung Kim, Hanyang Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 7216:
Gallium Nitride Materials and Devices IV
Hadis Morkoç; Cole W. Litton; Jen-Inn Chyi; Yasushi Nanishi; Joachim Piprek; Euijoon Yoon, Editor(s)

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