A universal method of producing transparent electrodes using wide-bandgap materials

Hee Dong Kim, Ho Myoung An, Kyoung Heon Kim, Su Jin Kim, Chi Sun Kim, Jaehee Cho, E. Fred Schubert, Tae Geun Kim

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31 Citations (Scopus)

Abstract

A UV light-emitting diode (LED) is an eco-friendly optical source with diverse applications. However, currently, the external quantum efficiency (EQE) of AlGaN-based UV LEDs, particularly in the UV-C band (<280 nm), is very low (<11%) mainly due to a large optical absorption via p-GaN contact layers. A direct Ohmic contact to p-AlGaN layers should be obtained using UV-transparent conductive electrodes (TCEs) to solve this problem. A universal method is presented here to make such contact using electrical breakdown, with wide-bandgap materials, to form conductive filaments (CFs), providing a current path between the TCEs and the p-(Al)GaN layers. The contact resistance between the TCEs and the p-GaN layers (or p-AlGaN) is found to be on the order of 10-5 Ω cm2 (or 10-3 Ω cm 2), while optical transmittance is maintained up to 95% for AlN-based TCEs at 250 nm. These findings could be a critical turning point delivering a breakthrough in UV LED technologies. A universal method of producing transparent conductive electrodes (TCEs) with high conductivity and high optical transmittance in the UV regimes is presented using electrical breakdown to form conducting filaments (CFs) providing a current path between the TCEs and the semiconductor, which leads to a direct ohmic contact to p-Al 0.5Ga0.5N layer as well as high optical transmittance of over 95% at 250 nm.

Original languageEnglish
Pages (from-to)1575-1581
Number of pages7
JournalAdvanced Functional Materials
Volume24
Issue number11
DOIs
Publication statusPublished - 2014 Mar 19

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Keywords

  • LEDs
  • conducting filaments
  • transparent conductive electrodes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Kim, H. D., An, H. M., Kim, K. H., Kim, S. J., Kim, C. S., Cho, J., Schubert, E. F., & Kim, T. G. (2014). A universal method of producing transparent electrodes using wide-bandgap materials. Advanced Functional Materials, 24(11), 1575-1581. https://doi.org/10.1002/adfm.201301697