IEEE Photonics Journal (Jan 2017)

Enhancing the Light-Extraction Efficiency of an AlGaN Nanowire Ultraviolet Light-Emitting Diode by Using Nitride/Air Distributed Bragg Reflector Nanogratings

  • Mohd Sharizal Alias,
  • Bilal Janjua,
  • Chao Zhao,
  • Davide Priante,
  • Abdullah A. Alhamoud,
  • Malleswararao Tangi,
  • Lafi M. Alanazi,
  • Abdullah A. Alatawi,
  • Abdulrahman M. Albadri,
  • Ahmed Y. Alyamani,
  • Tien Khee Ng,
  • Boon S. Ooi

DOI
https://doi.org/10.1109/JPHOT.2017.2749198
Journal volume & issue
Vol. 9, no. 5
pp. 1 – 8

Abstract

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The performance and efficiency of AlGaN ultraviolet light-emitting diodes have been limited by the extremely low light-extraction efficiency (LEE) due to the intrinsic material properties of AlGaN. Here, to enhance the LEE of the device, we demonstrate an AlGaN nanowire light-emitting diode (NW-LED) integrated with nitride/air distributed Bragg reflector (DBR) nanogratings. Compared to a control device (only mesa), the AlGaN NW-LED with the nitride/air DBR nanogratings exhibits enhancement in the light output power and external quantum efficiency (EQE) by a factor of ∼1.67. The higher light output power and EQE are attributed mainly to the multiple reflectances laterally for the transverse magnetic (TM)-polarized light and scattering introduced by the nanogratings. To further understand the LEE enhancement, the electrical field distribution, extraction ratio, and polar pattern of the AlGaN NW-LED with and without the nitride/air DBR nanogratings were analyzed using the finite-difference time-domain method. It was observed that the TM-field emission was confined and scattered upward, whereas the polar pattern was intensified for the AlGaN NW-LED with the nanogratings. Our approach to enhance the LEE via the nitride/air DBR nanogratings can provide a promising route for increasing the efficiency of AlGaN-based LEDs, also, to functioning as facet mirror for AlGaN-based laser diodes.

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