Cryst. Res. Technol. 44, No. 10, 1089 – 1094 (2009) / DOI 10.1002/crat.200900473 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Spatially resolved X-ray diffraction as a tool for strain analysis in laterally modulated epitaxial structures A. Wierzbicka* 1 , J. Z. Domagala 1 , M. Sarzynski 2 , and Z. R. Zytkiewicz 1 1 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02 668 Warszawa, Poland 2 Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01 142 Warszawa, Poland Received 3 August 2009, accepted 24 August 2009 Published online 11 September 2009 Key words X-ray micro-imaging, epitaxial lateral overgrowth, X-ray diffraction. PACS 61.05.cp, 68.55.ag, 68.60.Bs Spatially resolved X-ray diffraction (SRXRD) is applied for micro-imaging of strain in laterally modulated epitaxial structures. In GaAs layers grown by liquid phase epitaxial lateral overgrowth (ELO) on SiO 2 - masked GaAs substrates a downward tilt of ELO wings caused by their interaction with the mask is observed. The distribution of the tilt magnitude across the wings width is determined with µm-scale spatial resolution. This allows measuring of the shape of the lattice planes in individual ELO stripes. If a large area of the sample is studied the X-ray imaging provides precise information on the tilt of an individual wing and its distribution. In heteroepitaxial GaSb/GaAs ELO layers local mosaicity in the wing area is found. By the SRXRD the size of microblocks and their relative misorientation were analyzed. Finally, the SRXRD technique was applied to study distribution of localized strain in AlGaN epilayers grown by MOVPE on bulk GaN substrates with AlN mask. X-ray mapping proves that by mask patterning strain in AlGaN layer can be easily engineered, which opens a way to produce thicker, crack-free AlGaN layers with a higher Al content needed in GaN-based laser diodes. All these examples show that high spatial and angular resolutions offered by SRXRD makes the technique a powerful tool to study local lattice distortions in semiconductor microstructures. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65 th birthday © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Modern semiconductor electronics requires fast techniques that allow precise analysis of structural quality of crystalline materials, starting from bare wafers up to complicated 3D semiconductor structures. Moreover, due to miniaturization of semiconductor devices, techniques needed should allow detection and visualization of µm-size crystalline lattice defects. The later requirement is fulfilled by the X-ray Rocking Curve Imaging (RCI), based on synchrotron X-ray diffraction, which offers direct imaging of an extended sample area with a very high spatial resolution [1]. However, for most crystal growers easily accessible laboratory techniques are preferred. Therefore, we have developed a micro-imaging technique based on spatially resolved X-ray diffraction (SRXRD) that makes use of conventional high resolution X-ray diffractometer. In order to show a potential of the technique when applied for analysis of crystalline microstructures three examples will be presented in this report. First, we focus on SRXRD studies of epitaxial laterally overgrown (ELO) GaAs layers grown by liquid phase epitaxy (LPE) on SiO 2 -masked GaAs substrates. ELO layer consists of a few hundreds micrometers wide monocrystalline stripes regularly arranged on a substrate. Since each stripe is strained such samples contain a periodic distribution of strain and/or defects. High spatial and angular resolutions of SRXRD allow studying an effect of ELO wings tilt towards the mask. Direction of the tilt and the distribution of tilt magnitude across width of each wing were determined. Moreover, a dispersion of wing ____________________ * Corresponding author: e-mail: czyzak@ifpan.edu.pl