Reduced defect densities in the ZnO epilayer grown on Si substrates by laser-assisted molecular-beam epitaxy using a ZnS epitaxial buffer layer

T. Onuma, S. F. Chichibu, A. Uedono, Y. Z. Yoo, T. Chikyow, T. Sota, M. Kawasaki, H. Koinuma

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Abstract

Nonradiative photoluminescence (PL) lifetime (τnr) and point defect density in the (0001) ZnO epilayer grown on (111) Si substrates by laser-assisted molecular-beam epitaxy (L-MBE) using a (0001) ZnS epitaxial buffer layer were compared with those in the ZnO films on (111) and (001) Si substrates prepared by direct transformation of ZnS epilayers on Si by thermal oxidation [Yoo et al., Appl. Phys. Lett. 78, 616 (2001)]. Both the ZnO films exhibited excitonic reflectance anomalies and corresponding PL peaks at low temperature, and the density or size of vacancy-type point defects (Zn vacancies), which were measured by the monoenergetic positron annihilation measurement, in the L-MBE epilayer was lower than that in the films prepared by the oxidation transformation. The ZnO epilayer grown on a (0001) ZnS epitaxial buffer on (111) Si exhibited longer τnr of 105 ps at room temperature.

Original languageEnglish
Pages (from-to)5586-5588
Number of pages3
JournalApplied Physics Letters
Volume85
Issue number23
DOIs
Publication statusPublished - 2004 Dec 6

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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