AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS1-TuP

Paper PS1-TuP9
Improvement of External Efficiency using Surface Roughening Technique in the GaN-Based Light Emitting Diodes

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Etching of High-K, Compound Semiconductors and Advanced Materials Poster Session
Presenter: H.C. Lee, Sungkyunkwan University, Korea
Authors: H.C. Lee, Sungkyunkwan University, Korea
J.B. Park, Sungkyunkwan University, Korea
J.W. Bae, Sungkyunkwan University, Korea
G.Y. Yeom, Sungkyunkwan University, Korea
Correspondent: Click to Email
Gallium nitride based materials have attracted considerable interest in relation to their potential use in optoelectronic devices, such as light emitting diodes(LEDs) and laser diodes. Recently, as the brightness of GaN-based LEDs has increased, applications such as displays, traffic signals, backlights for cell phones, exterior automotive lighting, and printers have become possible. In general, the internal quantum efficiency for GaN-based LEDs is far smaller than 100% at room temperature due to the activation of nonradiative defects and it is also well known that the external quantum efficiency is still much smaller than the internal quantum efficiency. The external quantum efficiency of GaN-based LEDs is low because the refractive index of the nitride epitaxial layer differ greatly from that of the air. The refractive indexes of GaN and air are 2.5 and 1.0, respectively. The critical angle for the light generated in active region to escape is about 23degree. Surface roughening of a LEDs is one of the methods for improving the light extraction. Fujii reported an increase in the extraction efficiency of GaN-based light emitting diodes by surface roughening. In this study, we investigated on the improved light output and electrical performance of a GaN-based LEDs by a roughened surface using etching technique. The light output efficiency of a LEDs structure with a roughened surface was significantly increased compared to that of a before roughened LEDs structure. The structural and electrical properties of the surface roughened of the LEDs were evaluated using a scanning electron microscope and a HP4145A probing system. Optical properties such as intensity and wavelength of the emitting-light was observed by an optical emission spectroscopy(OES). Output power of samples was measured by an optical powermeter.