Point defects in Si thin films grown by molecular beam epitaxy

H. J. Gossmann, P. Asoka-Kumar, T. C. Leung, B. Nielsen, K. G. Lynn, F. C. Unterwald, L. C. Feldman

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36 Citations (Scopus)

Abstract

Depth profiles of vacancylike defects have been determined by positron annihilation spectroscopy in 200-nm-thick Si films grown by molecular beam epitaxy on Si(100) substrates at growth temperatures Tgrowth=200- 560°C. The line shape of the radiation emitted from implanted positrons annihilating in the near-surface region of a solid gives quantitative, depth-resolved information on defect concentrations in a nondestructive way. In particular, the method is sensitive to vacancylike defects in a concentration range inaccessible to electron microscopy or ion scattering, but important for electrical device characteristics. The sensitivity limit for these defects in the present experiments is estimated as 5×1015 cm-3. Films grown at Tgrowth≥475±20°C are indistinguishable from virgin wafers. So are samples with Tgrowth=220±20°C, subjected to a 2 min, TRTA≳500°C rapid thermal anneal (RTA) after every ≊30 nm of Si growth. If TRTA=450±20°C, part of the film contains a concentration of vacancylike defects on the order of 1018 cm-3. Our results indicate the importance of the growth parameters, such as temperature and substrate preparation, for the production of high quality films.

Original languageEnglish
Pages (from-to)540-542
Number of pages3
JournalApplied Physics Letters
Volume61
Issue number5
DOIs
Publication statusPublished - Dec 1 1992

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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