Effects of Mesa Size on Current Spreading and Light Extraction of GaN-Based LEDs

The mesa size effect on light extraction efficiency (LEE) of light-emitting diodes (LEDs) was studied in this work. The mesa area size of three kinds of LEDs that were evaluated include: 350×950 μm
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(small-size embedded electrodes: GaN LED, S-LED), 500×950 μm
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(medium-size embedded electrodes: GaN LED, M-LED), 950×950 μm
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(large-size embedded electrodes : GaN LED, L-LED). This paper not only discusses LEE, but current density and heat dissipation performance as well. The output power and light extraction efficiency at 700 mA/mm
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for S-LED, M-LED, and L-LED are 555, 485, and 432 mW and 38.1%, 33.4%, and 29.7%, respectively. The best output power and LEE of S-LED is due to the electron-hole recombination rate increasing. This phenomenon is caused by the greatest current spread and heat dissipation potential.