Influence of Interfacial Effects on X-ray Diffraction Spectra of the [GaAs]_n[AlAs]_mSuperlattices

Abstract

Influence of interdiffusion, terrace growth, and macroscopic uniformity on X-ray diffraction spectra of [GaAs]n[A1As] m superlattices are presented. High--angle spectra are analysed on the basis of the kinematic theory of diffraction, whereas low-angle spectra are analysed using the dynamic theory. Computer--simulated (using a Monte-Carlo method) spectra based on a "statistical" mode1 of the superlattice structure are applied in the analysis.PACS numbers: 61.10.Dp, 68.65.+g X-ray diffraction measurements are frequently used to examine stuctural parameters of semiconductor superlattices -mainly because the X-ray differaction spectra are very sensitive to interfacial effects [1]. These measurements are nondestructive and relatively simple but precise analysis of the spectra is difficult because we obtain a complicated image resulting from the influence of different stuctural parameters: average numbers of monolayers in the superlattice unit cell, fluctuations of these values, thickness of interdiffused region at the interface, the macroscopic uniformíty of the multilayer across the film, etc [2][3][4].For the precise quantitative description of the interfacial effects high-and low-angle X-ray diffraction spectra should be examined. The high-angle spectra can be interpreted on the basis of the kinematic theory of diffraction, whereas the low-angle spectra should be analysed using the dynamic theory. The [GaAs]n [AlAs]m superlattices have been studied more extensively than any other multilayer system [5][6][7][8][9]. Hence, in this work, the author focusses on the influence of the interfacial effects on high-and low-angle X-ray diffraction spectra of [GaAs]n [AlAs] m superlattices. The computer-simulated (using a Monte-Carlo method) spectra based on a "statistical" model of the superlattice stucture are proposed in the analysis.