Title :
Efficiency improvement of AlGaInN LEDs advanced by ray-tracing analysis
Author :
Zabelin, Vasily ; Zakheim, Dmitri A. ; Gurevich, Sergey A.
Author_Institution :
A.F. Ioffe Physico-Tech. Inst., Russian Acad. of Sci., St. Petersburg, Russia
Abstract :
A modified ray-tracing model is applied to analyze the dependence of external quantum efficiency and far-field radiation pattern of AlGaInN light-emitting diodes (LEDs) on various device parameters. Considerable increase (about 1.5 times) in the efficiency is predicted for LEDs with highly reflective p-contact as compared to those with the semitransparent p-contact. It is shown that the LED´s efficiency degrades with the increasing of the optical loss in AlGaInN epitaxial layers as well as with increasing of the LED chip area. The ways of improving the external efficiency of large-area (and thus, powerful) LEDs are discussed including utilization of a textured (light-scattering) backside of sapphire substrate or a diffusive interface between epitaxial layers and p-contact.
Keywords :
III-V semiconductors; aluminium compounds; electrical contacts; gallium compounds; indium compounds; light emitting diodes; light scattering; optical losses; ray tracing; semiconductor device models; semiconductor epitaxial layers; AlGaInN; AlGaInN LED; AlGaInN epitaxial layers; LED chip area; LED efficiency; diffusive interface; external quantum efficiency; far-field radiation pattern; light scattering; light-emitting diodes; modified ray-tracing model; optical loss; ray-tracing analysis; reflective p-contact; sapphire substrate; Degradation; Epitaxial layers; Light emitting diodes; Light scattering; Optical losses; Optical reflection; Optical scattering; Pattern analysis; Ray tracing; Substrates; 65; Electromagnetic scattering; LEDs; light-emitting diodes; semiconductor device modeling;
Journal_Title :
Quantum Electronics, IEEE Journal of
DOI :
10.1109/JQE.2004.837005
