Size effect on negative capacitance at forward bias in InGaN/GaN multiple quantum well-based blue LED

El Mostafa Bourim, Jeong In Han

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Size effect of InGaN/GaN multiple quantum well (MQW) blue light emitting diodes (LEDs), on electrical characteristics in forward bias voltage at high injection current in light emission regime, is observed to induce a substantial dispersion in the current density and normalized negative capacitance (NC) (i.e., capacitance per chip area). The correction of normalized NC by considering the LED p-n junction series resistance has been found to be independent of chip area size with lateral dimensions ranging from 100 µm × 100 µm to 400 µm × 400 µm. This fact, confirms that the inductive effect which is usually behind the NC apparition is homogeneously and uniformly distributed across the entire device area and hence the dispersive characteristics are not related to local paths. From the characteristics of NC dependence on temperature, frequency and direct current bias, a mechanism based on the electrons/holes charge carriers conductivity difference is proposed to be responsible for the transient electron-hole pair recombination process inducing NC phenomenon. Direct measurement of light emission brightness under modulated frequency demonstrated that modulated light output evolution follows the same behavioral tendency as measured in NC under alternating current signal modulation. Thus it is concluded that the NC is valuable information which would be of practical interest in improving the characteristics and parameters relevant to LED p-n junction internal structure. [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)67-75
Number of pages9
JournalElectronic Materials Letters
Volume12
Issue number1
DOIs
StatePublished - 1 Jan 2016

Keywords

  • admittance spectroscopy
  • electron-hole recombination
  • InGaN/GaN
  • LED
  • negative capacitance

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