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Phys. Rev. B 66, 205411 (2002) [7 pages]

Epitaxy and strain in the growth of GaN on AlN: A polarized x-ray absorption spectroscopy study

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F. d’Acapito *
Istituto Nazionale per la Fisica della Materia – Operative Group in Grenoble c/o European Synchrotron Radiation Facility, Boîte Postale 220, F-38043 Grenoble, France

F. Boscherini
Istituto Nazionale per la Fisica della Materia and Dipartimento di Fisica, Universita’ di Bologna, Viale C. Berti Pichat 6/2, I - 40127 Bologna, Italy

S. Mobilio †
Dipartimento di Fisica, Universita’ Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy

A. Rizzi ‡
Istituto Nazionale per la Fisica della Materia and Dipartimento di Fisica, Universita’ di Modena e Reggio Emilia, via G. Campi, I-41100 Modena, Italy

R. Lantier
Istitut für Schichten und Grenzflachen, Forschungszentrum Julich, D-52425 Julich, Germany

Received 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

* Electronic address: dacapito@esrf.fr
† Also at INFN, Laboratori Nazionali di Frascati, P.O. Box 13, I-00044 Frascati (Roma), Italy.
‡ Also at ISG, Forschungszentrum Julich, D-52425 Julich, Germany.

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