Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes

An Jye Tzou, Bing Cheng Lin, Chia Yu Lee, Da Wei Lin, Yu Kuang Liao, Zhen Yu Li*, Gou Chung Chi, Hao-Chung Kuo, Chun Yen Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Crack-free GaN-based light-emitting diodes (LEDs) were grown on 150-mm-diameter Si substrates by using low-pressure metal-organic chemical vapor deposition. The relationship between the LED devices and the thickness of quantum barriers (QBs) was investigated. The crystal quality and surface cracking of GaN-on-Si were greatly improved by an AlxGa1-xN buffer layer composed of graded Al. The threading dislocation density of the GaN-on-Si LEDs was reduced to <7 × 108 cm-2, yielding LEDs with high internal quantum efficiency. Simulation results indicated that reducing the QB thickness improved the carrier injection rate and distribution, thereby improving the droop behavior of the LEDs. LEDs featuring 6-nm-thick QBs exhibited the lowest droop behavior. However, the experimental results showed an unanticipated phenomenon, namely that the peak external quantum efficiency (EQE) and light output power (LOP) gradually decreased with a decreasing QB thickness. In other words, the GaN-on-Si LEDs with 8-nm-thick QBs exhibited low droop behavior and yielded a good peak EQE and LOP, achieving a 22.9% efficiency droop and 54.6% EQE.

Original languageEnglish
Article number14089SS
JournalJournal of Photonics for Energy
Volume5
Issue number1
DOIs
StatePublished - 19 Jan 2015

Keywords

  • droop behavior improvement
  • external quantum efficiency
  • GaN-on-Si
  • light-emitting diodes
  • thin barrier

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