DOI: 10.1021/cg1004006
X-ray Bragg-Surface Diffraction: A Tool to Study In-Plane Strain Anisotropy Due to Ion-Beam-Induced Epitaxial Crystallization in Feþ-Implanted Si(001)
2010, Vol. 10 4363–4369
Rossano Lang,†,‡ Alan S. de Menezes,§ Adenilson O. dos Santos,§,# Shay Reboh,†,‡ Eliermes A. Meneses,§ Livio Amaral,† and Lisandro P. Cardoso*,§ Programa de P os-Graduac-a~o em Ci^ encias dos Materiais (PGCIMAT ), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil, ‡Instituto de Fı´sica, Universidade Federal do Rio Grande do Sul (UFRGS), 191501-970 Porto Alegre, Rio Grande do Sul, Brazil, § Instituto de Fı´sica Gleb Wataghin, Universidade Estadual de Campinas - UNICAMP, 13083-970 encias Sociais, Sa ude e Tecnologia (CCSST ), Campinas, S~ ao Paulo, Brazil, and #Centro de Ci^ Universidade Federal do Maranh~ ao, 65900-410 Imperatriz, Maranh~ ao, Brazil †
Received March 25, 2010; Revised Manuscript Received August 9, 2010
ABSTRACT: In-plane strain anisotropy was clearly observed by the X-ray Bragg-surface diffraction technique in the silicon lattice surrounded by nanoparticles that were synthesized by an ion-beam-induced epitaxial recrystallization process of Fe-implanted amorphous Si layer. High resolution transmission electron microscopy images have shown the occurrence of metallic spherical and plate-like γ-FeSi2 nanoparticles in the implanted/recrystallized region. These were found in different orientations within the sample, being responsible for the strain anisotropy detected. The striking anisotropy effect, due to mainly the plate-like nanoparticles in the recrystallized region, appears when comparing two (-6.04 and 83.96) (002) rocking curves at Bragg-surface diffraction exact condition. Furthermore, the mappings of the (111) Bragg-surface diffraction reflections show an evident anisotropy between φ = -6.04 and 83.96 mappings and also a marked broadening of the implanted sample profile as compared to that of the Si (matrix). Reciprocal space maps obtained for both perpendicular directions clearly exhibit this anisotropic effect in the qx direction, thus confirming the Bragg-surface diffraction results.
*To whom correspondence should be addressed. E-mail: cardoso@ifi. unicamp.br.
techniques to evaluate lattice strain distributions quantitatively at the nanometric scale. Lattice strain is usually measured by conventional X-ray diffraction and micro-Raman scattering spectroscopy techniques.14,15 However, their spatial resolution is insufficient to meet this recent demand. A very useful, high resolution, and versatile technique has been developed and successfully applied as a three-dimensional (3D) probe to study single crystals in general, and with very interesting contributions to the semiconductor epitaxial systems - the X-ray multiple diffraction (XRMD) technique.16 It is a powerful tool based on the simultaneous diffraction of an incident X-ray beam by different crystallographic planes of a single crystal. As these planes are parallel (primary) and inclined (secondary) with respect to the crystal surface, XRMD provides 3D information on the analyzed crystalline lattice, given that different beam orientations at different depths within the crystal are simultaneously observed. It has already been applied to study dislocations at the interface plane of a GaAs layer on top of a Si substrate,17 as well as lattice coherence in InGaP/GaAs(001) with the detection of very small changes (
