Structure and optical properties of Ge-Si ordered superlattices

J. Bevk, A. Ourmazd, Leonard C Feldman, T. P. Pearsall, J. M. Bonar, B. A. Davidson, J. P. Mannaerts

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Abstract

We report the synthesis, structural characterization, and optical studies of ultrathin Ge-Si superlattices, grown by molecular beam epitaxy, on (001) silicon substrates. Structures consist of alternating layers of pure Ge and Si, with layer thicknesses of 1, 2, 4, and 6 monolayers. Using high-resolution transmission electron microscopy, we provide direct observation of order in these pseudomorphic layered films. Systematic study of optical transitions by means of Schottky barrier electroreflectance reveals that each of the ordered structures displays a unique set of optical transitions. Of particular interest is the 4×4 structure which shows new, well defined optical transitions at 0.76, 1.25, and 2.31 eV. These transitions constitute the first observation of structurally induced optical transitions in Ge-Si and may make the 4×4 structure suitable for optoelectronic devices.

Original languageEnglish
Pages (from-to)760-762
Number of pages3
JournalApplied Physics Letters
Volume50
Issue number12
DOIs
Publication statusPublished - 1987

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Bevk, J., Ourmazd, A., Feldman, L. C., Pearsall, T. P., Bonar, J. M., Davidson, B. A., & Mannaerts, J. P. (1987). Structure and optical properties of Ge-Si ordered superlattices. Applied Physics Letters, 50(12), 760-762. https://doi.org/10.1063/1.98037