Coherent diffraction imaging of a single epitaxial InAs nanowire

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The cross-section of an InAs nanowire with a diameter of 150 nm epitaxially grown on a 111-oriented InP substrate was characterized using a combination of x-ray scanning micro-diffraction and coherent diffraction imaging. Using an x-ray beam focused by a Fresnel zone plate, we were able to scan in real space and hence localize single nanowires on the substrate in the as-grown epitaxial state. For one single nanowire, the three-dimensional coherent intensity distribution in reciprocal space was mapped around the (111) InAs reflection. Using phase retrieval algorithms, the cross-section of the wire was reconstructed with a spatial resolution of 8 nm along one direction.ngle epitaxial InAs nanowire using a focused x-ray beam

Figure 1a: 2D cut of the 3D reciprocal space map recorded around the (111) reflection of a single InAs nanowire.
Figure 1b: Experimental setup. The focused x-ray beam is 350 nm 400nm(VH). The nanowire, epitaxially grown on an InP substrate, has a diameter of 150 nm and a height of a few microns.
Figure 1c: electron density of the nanowire cross section directly reconstructed from the data shown in (a) by means of iterative phase retrieval algorithms. The dashed line indicates the support used in the reconstruction.

Authors: A. Diaz^1,2, C. Mocuta¹, J. Stangl², B. Mandl², C. David³, J. Vila-Comamala³, V. Chamard⁴, T.H. Metzger¹ and G. Bauer²
_{1 ESRF, Grenoble (France), 2 Institut für Halbleiterphysik, Linz (Austria), 3PSI, Villigen (Switzerland), 4CNRS Marseille (France)}

Ref: Phys. Rev. B 79, 125324 (2009)