Fast nanoscale imaging of strain in a multi-segment heterostructured nanowire with 2D Bragg ptychography

Hammarberg, S.; Dzhigaev, D.; Marcal, L.A.B.; Dagyte, V.; Björling, A.; Borgström, M.T.; Wallentin, J.

doi:10.1107/S1600576723010403

Figure 1
(a) Sketch of the BPP experiment. The heterostructured nanowire lies flat on a substrate and is placed horizontally in the beam with the gold growth seed particle to the left. The nanowire is in the Bragg condition for the {111} lattice planes, which are orthogonal to the nanowire axis. Thus, the scattering vector q is parallel with the nanowire axis. The nanowire is translated in the nanofocused beam along x and y, whereas the scattered signal is measured with a 2D detector in the far field in the measurement coordinate system (q₁, q₂, q₃). The x and y translation is repeated at different rotations in θ_B. (b) Lineout of the nanowire showing the nominal lengths of the five InP segments in the GaInP nanowire. The segments are denoted with numbers from left to right, segments 1–5. (c) Summed intensity as a function of rotation θ_B (rocking curves) from the five respective InP segments in logscale. The vertical lines indicate the Bragg angles $[\theta_{\rm B}^{1 - 5}]$ , chosen from the maximum of Gaussian fits to the peaks, except for $[\theta_{\rm B}^{5}]$ where the maximum intensity point was chosen. (d) 2D cuts of axial strain $[\varepsilon_{xx}]$ from a 3D FEM model. Positive values of $[\varepsilon_{xx}]$ correspond to tensile strain in the axial direction.

JOURNAL OF
APPLIED
CRYSTALLOGRAPHY

ISSN: 1600-5767

Volume 57| Part 1| February 2024| Pages 60-70

https://doi.org/10.1107/S1600576723010403

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