3D imaging of GaN nano dots (~17nm) by coherent X-ray diffraction

By combining coherent X-ray scattering with a method of direct phase recovery called over-sampling, lens-free microscopy in the X-ray region becomes a realistic technique. The latest hot topic is the extension of the technique from two to three dimensions. One of the most promising ways of applying this technique is the recently reported combination of (i) ab initio phase retrieval of 2D coherent diffraction patterns with a guided hybrid input-output algorithm and (ii) 3D image reconstruction with equally sloped tomography. The scheme was applied to quantitative 3D imaging of a heat-treated GaN particle with each voxel corresponding to 17×17×17 nm³. The internal GaN-Ga₂O₃ core shell structure was successfully captured in three dimensions. For more information about the analysis, see the paper, "Three-Dimensional GaN-Ga₂O₃ Core Shell Structure Revealed by X-Ray Diffraction Microscopy", J. Miao et al., Phys. Rev. Lett. 97, 215503 (2006).