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Semiconductors

, Volume 40, Issue 1, pp 118–123 | Cite as

Nonuniformity of carrier injection and the degradation of blue LEDs

  • N. I. Bochkareva
  • A. A. Efremov
  • Yu. T. Rebane
  • R. I. Gorbunov
  • A. V. Klochkov
  • Yu. G. Shreter
Physics of Semiconductor Devices

Abstract

The distribution of electroluminescence (EL) intensity over the area and in the course of time before and after the optical degradation of blue InGaN/GaN LEDs is studied. Current-voltage characteristics have been recorded. It is found that the initially bright luminescence near the region of metallization of the p-contact turns weak after the degradation of an LED. The time delay of ∼20–40 ns is observed in the distribution of EL intensity over the area of LEDs after their degradation. We suppose that a rise in the excess current after degradation is due to the density increasing of the InGaN/GaN interface states and the formation of an electrical dipole, which lowers the potential barriers in p-GaN and n-GaN layers. The corresponding increase of capacitance leads to a time delay in the spreading of the injection current and in the distribution of the emission brightness over the area. The lateral nonuniformity of the carrier injection into the quantum, well before and after optical degradation, is attributed to diffusion and electromigration of hydrogen, induced by mechanical stress. The metallization of the p-contact may be the source of mechanical stress.

Keywords

Hydrogen Time Delay Magnetic Material Mechanical Stress Potential Barrier 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Pleiades Publishing, Inc. 2006

Authors and Affiliations

  • N. I. Bochkareva
    • 1
  • A. A. Efremov
    • 2
  • Yu. T. Rebane
    • 1
  • R. I. Gorbunov
    • 1
  • A. V. Klochkov
    • 1
  • Yu. G. Shreter
    • 1
  1. 1.Ioffe Physicotechnical InstituteRussian Academy of SciencesSt. PetersburgRussia
  2. 2.St. Petersburg State Polytechnical UniversitySt. PetersburgRussia

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