Phys. Rev. B 66, 205411 (2002) [7 pages]Epitaxy and strain in the growth of GaN on AlN: A polarized x-ray absorption spectroscopy studyReceived 29 September 2001; revised 23 April 2002; published 25 November 2002 We present a study of the local structure of 7–8 nm thick GaN epilayers deposited on AlN by molecular beam epitaxy at temperatures ranging between 620 and 790°C by x-ray absorption spectroscopy, exploiting the polarization dependence of the technique. Both the near-edge and extended spectra suggest that atomic intermixing between GaN and AlN takes place at most for one monolayer. An interpretation of the near-edge spectra of wurtzite GaN and of the variation with the sample orientation in the framework of multiple scattering theory is provided. Values of the in-plane and out-of-plane strain due to heteroepitaxial growth are obtained from the interatomic distances in the second coordination shell around Ga; we compare the obtained values to literature values of the elastic constants, finding good agreement with most of them. © 2002 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.66.205411
DOI:
10.1103/PhysRevB.66.205411
PACS:
61.10.Ht, 62.20.Dc, 81.05.Ea
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