Consideration of the actual current-spreading length of gaN-based light-emitting diodes for high-efficiency design

Hyunsoo Kim, Jaehee Cho, Jeong Wook Lee, Sukho Yoon, Hyungkun Kim, Cheolsoo Sone, Yongjo Park, Tae Yeon Seong

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Based on the proposed experimental method, the current spreading length of GaN-based light-emitting diodes (LEDs) was measured and analyzed for practical device design. In this study, Thompson's and Guo's models, which are categorized according to vertical series resistance (in particular, p-type contact resistance), were used to extract device parameters. It was shown that the measured current spreading length strongly depends on the injected current density. For LEDs fabricated with low-resistance p-type contacts, this behavior could be explained in terms of the accelerated current crowding with higher current densities occurring as a result of the reduced voltage drop across the junction, which is in good agreement with Thompson's relation. However, for LEDs fabricated with high-resistance p-contacts, unlike Guo's prediction, the measured current spreading length also showed a strong dependence on the injected current density. This was attributed to thermal heating at the p-contact, resulting in the reduction of the voltage drop across the p-contact and so junction voltage, which is also in agreement with Thompson's model. Based on the measured parameters and the design rule, efficient p-type reflectors, namely, hybrid reflectors were designed. Compared with conventional ones, LEDs fabricated with the hybrid reflectors exhibited better output power at a reasonable forward voltage, indicating that the proposed method is effective in understanding the actual current spreading and hence the practical design of high-efficiency LEDs.

Original languageEnglish
Pages (from-to)625-632
Number of pages8
JournalIEEE Journal of Quantum Electronics
Volume43
Issue number8
DOIs
Publication statusPublished - 2007 Aug 1

Fingerprint

Light emitting diodes
light emitting diodes
reflectors
Current density
electric potential
Contact resistance
current density
crowding
low resistance
high resistance
Electric potential
contact resistance
high current
Heating
heating
output
predictions
Voltage drop

Keywords

  • Current crowding
  • Design
  • GaN
  • Light-emitting diode (LED)
  • Reflector

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Physics and Astronomy (miscellaneous)

Cite this

Consideration of the actual current-spreading length of gaN-based light-emitting diodes for high-efficiency design. / Kim, Hyunsoo; Cho, Jaehee; Lee, Jeong Wook; Yoon, Sukho; Kim, Hyungkun; Sone, Cheolsoo; Park, Yongjo; Seong, Tae Yeon.

In: IEEE Journal of Quantum Electronics, Vol. 43, No. 8, 01.08.2007, p. 625-632.

Research output: Contribution to journalArticle

Kim, Hyunsoo ; Cho, Jaehee ; Lee, Jeong Wook ; Yoon, Sukho ; Kim, Hyungkun ; Sone, Cheolsoo ; Park, Yongjo ; Seong, Tae Yeon. / Consideration of the actual current-spreading length of gaN-based light-emitting diodes for high-efficiency design. In: IEEE Journal of Quantum Electronics. 2007 ; Vol. 43, No. 8. pp. 625-632.
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