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Article

Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study

STR Group–Soft-Impact, Ltd., 64 Bolshoi Sampsonievskii pr., Bld. E., 194044 St. Petersburg, Russia
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Photonics 2018, 5(4), 41; https://doi.org/10.3390/photonics5040041
Received: 2 October 2018 / Revised: 22 October 2018 / Accepted: 25 October 2018 / Published: 27 October 2018
Flip-chip truncated-pyramid-shaped blue micro-light-emitting diodes (μ-LEDs), with different inclinations of the mesa facets to the epitaxial layer plane, are studied by simulations, implementing experimental information on temperature-dependent parameters and characteristics of large-size devices. Strong non-monotonous dependence of light extraction efficiency (LEE) on the inclination angle is revealed, affecting, remarkably, the overall emission efficiency. Without texturing of emitting surfaces, LEE to air up to 54.4% is predicted for optimized shape of the μ-LED dice, which is higher than that of conventional large-size LEDs. The major factors limiting the μ-LED performance are identified, among which, the most critical are the optical losses originated from incomplete light reflection from metallic electrodes and the high p-contact resistance caused by its small area. Optimization of the p-electrode dimensions enables further improvement of high-current wall-plug efficiency of the devices. The roles of surface recombination, device self-heating, current crowding, and efficiency droop at high current densities, in limitation of the μ-LED efficiency, are assessed. A novel approach implementing the characterization data of large-size LED as the input information for simulations is tested successfully. View Full-Text
Keywords: micro-LEDs; InGaN; light extraction efficiency; external quantum efficiency; surface recombination; current crowding; self-heating; simulation; optical losses micro-LEDs; InGaN; light extraction efficiency; external quantum efficiency; surface recombination; current crowding; self-heating; simulation; optical losses
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MDPI and ACS Style

Bulashevich, K.A.; Konoplev, S.S.; Karpov, S.Y. Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study. Photonics 2018, 5, 41. https://doi.org/10.3390/photonics5040041

AMA Style

Bulashevich KA, Konoplev SS, Karpov SY. Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study. Photonics. 2018; 5(4):41. https://doi.org/10.3390/photonics5040041

Chicago/Turabian Style

Bulashevich, Kirill A., Sergey S. Konoplev, and Sergey Y. Karpov 2018. "Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study" Photonics 5, no. 4: 41. https://doi.org/10.3390/photonics5040041

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