Size-dependent capacitance study on InGaN-based micro-light-emitting diodes

Wei Yang, Shuailong Zhang, Jonathan McKendry, Johannes Herrnsdorf, Pengfei Tian, Zheng Gong, Qingbin Ji, Ian Watson, Erdan Gu, Martin Dawson, Liefeng Feng, Cunda Wang, Xiaodong Hu

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Abstract

We report a detailed study on size-dependent capacitance, especially the negative capacitance (NC), in InGaN-based micro-pixelated light-emitting diodes (μLEDs). Similar to conventional broad-area LEDs, μLEDs show NC under large forward bias. In the conventional depletion and diffusion capacitance regimes, a good linear relationship of capacitance with device size is observed. However, the NC under high forward bias shows slight deviation from above-mentioned linear relationship with device size. This behaviour can be understood if the effects of current density and junction temperature on NC are considered. The measured temperature dependence and frequency dispersion of the capacitance underpin this point of view. The NCs of two reference broad-area LEDs were also measured and compared with that of μLED clusters with the same total size. A stronger NC effect is observed in the μLED clusters, which is attributed to the increased number of sidewall defects during fabrication process.
Original languageEnglish
Article number044512
Number of pages6
JournalJournal of Applied Physics
Volume116
Issue number4
Early online date29 Jul 2014
DOIs
Publication statusPublished - 2014

Keywords

  • light emitting diode
  • charge injection
  • gold

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