Blue light-emitting diode based on ZnO

Atsushi Tsukazaki, Masashi Kubota, Akira Ohtomo, Takeyoshi Onuma, Keita Ohtani, Hideo Ohno, Shigefusa F. Chichibu, Masashi Kawasaki

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431 Citations (Scopus)


A near-band-edge bluish electroluminescence (EL) band centered at around 440 nm was observed from ZnO p-i-n homojunction diodes through a semi-transparent electrode deposited on the p-type ZnO top layer. The EL peak energy coincided with the photoluminescence peak energy of an equivalent p-type ZnO layer, indicating that the electron injection from the n-type layer to the p-type layer dominates the current, giving rise to the radiative recombination in the p-type layer. The imbalance in charge injection is considered to originate from the lower majority carrier concentration in the p-type layer, which is one or two orders of magnitude lower than that in the n-type one. The current-voltage characteristics showed the presence of series resistance of several hundreds ohms, corresponding to the current spread resistance within the bottom n-type ZnO. The employment of conducting ZnO substrates may solve the latter problem.

Original languageEnglish
Pages (from-to)L643-L645
JournalJapanese Journal of Applied Physics
Issue number20-23
Publication statusPublished - 2005


  • Light-emitting diode
  • Pulsed laser deposition
  • Self-absorption
  • Thin film
  • ZnO


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