ISSN:
1600-5767
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Geosciences
,
Physics
Notes:
X-ray rocking-curve analysis of implanted silicon is commonly used to investigate damage accumulation with increasing ion dose. The damage build-up is observed by the trends of either the maximum of the lattice strain normal to the surface (ε.⊥) or the depth integral of the ε.⊥ profile. However, for doses high enough to produce a buried amorphous layer, the determination of the peak value of the ε.⊥ depth profile, and hence of its integral, is not possible. This is demonstrated by means of a simple diffraction model which describes the amorphous layer as a material for which the structure factor is reduced to zero by sufficiently high values of the static Debye-Waller factor and for which the expansion u normal to the surface is given by the product of the fractional change of the interplanar spacing of the perfect crystal (ε.⊥α) and the thickness of the amorphous layer (tα). Since this expansion can be written as u = ε.⊥αtα = (n + x)d, where n is an integer (n = 0, 1, 2, ...), 0 ≤ x 〈 1 and d is the spacing of the diffraction planes of the perfect crystal, the diffraction model shows that, for given thickness tα and fraction x of d, there exists a discrete, in principle infinite, set of u values able to give identical rocking curves. This prevents the rigid outward displacement of the damaged surface crystalline region with respect to the substrate from being determined.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0021889895007114
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