Three-dimensional coherent X-ray surface scattering imaging near total external reflection

Lensless X-ray coherent diffraction imaging (CDI) has emerged as a thriving field promising applications in materials and biological sciences(1-13) with a theoretical imaging resolution only limited by the X-ray wavelength. Most CDI methods use transmission geometry, which is not suitable for nanostructures grown on opaque substrates or for objects of interest comprising only surfaces or interfaces. Attempts have been made to perform CDI experiments in reflection geometry, both optically and with X-rays, but the reconstruction resulted in mostly planar images, with less success in the third dimension(14,15). Here, we discuss the development of coherent surface scattering imaging in grazing-incidence geometry that takes advantage of enhanced X-ray surface scattering and interference near total external reflection. We demonstrate the successful reconstruction of substrate-supported non-periodic surface patterns in three dimensions with nanometre resolution in the direction normal to the substrate, promising wide applications in elucidating structures in substrate-supported and buried nanoelectronics and photonics.