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X-ray multiple diffraction of ZnO substrates and heteroepitaxial thin films

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Abstract

We investigate Umweganregung reflections (X-ray multiple reflections) for math formula, (00.3), and (00.5) for a number of wurtzite structure ZnO samples, namely various bulk crystals (substrates), two ZnO thin films and a ZnO:Mg thin film, grown by pulsed laser deposition on a-plane sapphire. Using a low divergence setup, we achieve a high angular resolution of 0.1math formula or better. We derive an analytical formula for peak positions as a function of wavelength math formula and the lattice parameters a and c. The three investigated ZnO substrates exhibit all expected (kinematically allowed) reflections for Cu Kα1, Kα2, and Kβ. A lineshape analysis of the multiple reflection peaks shows that the width of certain reflections is determined by the spectral linewidth of the exciting copper lines. The thin films exhibit only slight broadening of the peaks but disappearance of several reflections. The a lattice constant can be determined from the azimuthal peak positions.

Umweganregung scan for math formula (math formula) of a hydrothermally grown ZnO substrate, excited with Cu Kα1 radiation. The pattern is symmetric with respect to zero angle representing the (10.0) azimuth. pssb201350297-gra-0001

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