J. Phys. I France 5 (1995) 111-127
Line-Shape Analysis of High Resolution X-Ray Diffraction Spectra of Finite Size Thue-Morse GaAs-AlAs Multilayer HeterostructuresJacques Peyrière1, Eric Cockayne2 and Françoise Axel2
1 Equipe d'Analyse Harmonique (CNRS - URA 757), Bât. 425, Université Paris-Sud, 91405 Orsay, France
2 Laboratoire de Physique des Solides (CNRS - URA 002), Bât. 510, Université Paris-Sud, 91405 Orsay, France
(Received 15 July 1994, received in final form 12 September 1994, accepted 26 September 1994)
We present a detailed and thorough theoretical and numerical line shape analysis of high resolution X-ray diffraction spectra of Thue-Morse GaAs-AlAs superlattice heterostructures having finite size ( 2n layers), which fully confirms the essentials of the preliminary analysis of previous work : Most of the peaks are labeled by the irreducible rationals k/(3.2m), k and m integers, in convenient units, the dependence of their intensity on sample size is governed by exponents and the diffraction spectrum retains the essential properties of a singular continuous measure. The effects of instrumental parameters is taken into account, in particular detector resolution effects. Furthermore we investigate the effects on the diffraction spectrum of MBE deposited layer roughness, represented by a random fluctuation of layer thickness.
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