Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-1103-C2-1105
DOI: 10.1051/jp4:19972148

Local Structural Distortions in InAsP/InP Strained Layer Superlattices

S. Pascarelli^{1, 2}, F. Boscherini³, C. Lamberti⁴ and S. Mobilio<sup>3, 5

1</sup>  Istituto Nazionale per la Fisica della Materia, Via dell'Acciaio 139, 16152 Genova, Italy
²  GILDA CRG, ESRF, BP. 220,38043 Grenoble cedex, France
³  Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, CP13, 00044 Frascati, Italy
⁴  Dipartimento di Chimica IFM Università di Torino, Via P. Giuria 7, 10148 Torino, Italy
⁵  Dipartimento di Fisica, Università "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy

Abstract
The local structure around As in thin InAs_xP_1-x strained layers in InAs_xP_1-x/InP superlattices has been probed by fluorescence detected XAFS as a function of composition, and compared to that found in unstrained, bulk samples of similar composition. Contributions up to the third coordination shell around As were clearly visible in the spectra and were analyzed taking into account the major multiple scattering contributions. Differences in the local structure between the thin strained films and the bulk alloys are expected to arise from tetragonal strain due to epitaxy with the substrate. Results are consistent with a picture in which long range order in the strained layers is mainly achieved via bond angle distortions, as first shell bond distances follow the measured and theoretically predicted values of the bulk alloys. Evidence of the influence of tetragonal distortion on the local structure appears in further coordination shells.

© EDP Sciences 1997