Direct correlation between the internal quantum efficiency and photoluminescence lifetime in undoped ZnO epilayers grown on Zn-polar ZnO substrates by plasma-assisted molecular beam epitaxy

D. Takamizu, Y. Nishimoto, S. Akasaka, H. Yuji, K. Tamura, K. Nakahara, T. Onuma, T. Tanabe, H. Takasu, M. Kawasaki, S. F. Chichibu

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38 Citations (Scopus)

Abstract

The equivalent internal quantum efficiency (inteq) at 300 K of the near-band-edge excitonic photoluminescence (PL) peak in ZnO epilayers grown by plasma-assisted molecular beam epitaxy on Zn-polar ZnO substrates was directly correlated with the PL lifetime (τPL) for the first time. This relation seems to be universal for O-polar ZnO films grown by other methods. Present homoepitaxial ZnO epilayers grown above 800 °C exhibited atomically flat surfaces, and the best full-width-at-half-maximum value of (0002) ZnO x-ray diffraction ω -rocking curves was 17.6 arcsec. The higherature growth also led to a long τPL of 1.2 ns at 300 K. As a result, a record high inteq value (9.6%) was eventually obtained under an excitation density of 5 W cm2 (He-Cd, 325.0 nm). The homoepitaxial Zn-polar ZnO films grown by molecular beam epitaxy are coming to be used for p-n junction devices.

Original languageEnglish
Article number063502
JournalJournal of Applied Physics
Volume103
Issue number6
DOIs
Publication statusPublished - 2008 Apr 8

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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