X-ray diffraction analysis of multilayer porous InP(001) structure
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CTION AND SCATTERING OF IONIZING RADIATIONS
XRay Diffraction Analysis of Multilayer Porous InP(001) Structure A. A. Lomova, V. I. Punegovb, A. L. Vasil’eva, D. Nohavicac, P. Gladkovc, A. A. Kartsev, and D. V. Novikovd a
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskiі pr. 59, Moscow, 119333 Russia email: [email protected] b Komi Research Center, Ural Division, Russian Academy of Sciences, ul. Pervomaіskaya 54, Syktyvkar, 167610 Russia c Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Prague, Czech Republic d German Electron Synchrotron DESY, Hamburg, Germany Received August 10, 2009
Abstract—Multilayer structures composed of four porous bilayers have been studied by highresolution Xray diffraction using synchrotron radiation, and the photoluminescence of these structures has been investigated at 4 K. The porous structures were formed by anodic oxidation of InP(001) substrates in aqueous HCl solu tion. The structural parameters of the sublayers were varied by changing the electrochemical etching mode (potentiostatic/galvanostatic). The Xray scattering intensity maps near the InP 004 reflection are obtained. A model for scattering from such systems is proposed based on the statistical dynamical diffraction theory. Theoretical scattering maps have been fitted to the experimental ones. It is shown that a mathematical anal ysis of the scattering intensity maps makes it possible to determine the structural parameters of sublayers. The reconstructed parameters (thickness, strain, and porosity of sublayers and the shape and arrangement of pores) are in satisfactory agreement with the scanning electron microscopy data. DOI: 10.1134/S1063774510020033
INTRODUCTION The Xray diffraction from porous crystals remains little studied. This is related both to the absence of sta ble and guaranteed model samples for study and to the difficulties in describing the scattering processes in 3Dlocally inhomogeneous structures. The pores in layers of singlecrystal substrates are similar to amor phous particles of various shapes or defects with zero polarizability. Generally, the scattering from such lay ers has Bragg and diffuse components. One specific feature of the diffraction from these objects is that, even despite the fairly high (>80%) porosity and large size (several nanometers) of pores, the remaining sin glecrystal framework is not distorted and can dynam ically scatter radiation. Most experiments with Xray diffraction and scat tering from porous materials were performed on sili con layers and films in view of the wide application of this material in micro and nanoelectronics. The first successful attempts of numerical simulation of rocking curves within the dynamic theory of scattering were carried out on thin porous р+Si(001) layers [1, 2]. Then it was shown that structural information can be derived from porous р–Si layers and porous superlat tices [3, 4]. An increase in the porous layer thickness leads to an increase in the diffuse c
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