Linear crystal defects called dislocations are one of the most fascinating concepts in materials science that govern mechanical and optoelectronic properties of many materials across a broad range of application [1-3]. Three-dimensional (3-D) study of dislocation network is in principle accessible by conventional tomographic and stereoscopic techniques in Transmission Electron Microscopy (TEM) [4,5]. In these techniques in general the need to tilt the specimen for acquiring image series over large tilt ranges remain however an intricate problem, in particular when diffraction contrast or sensitivity to electron beam are involved [6].

Here, a novel method in scanning TEM (STEM) is presented that provides a reliable and fast assessment of the 3-D configuration of dislocations using data acquired from just one sample tilt. This technique acquires a stereoscopic pair of images by selecting different ray paths of a convergent illumination in STEM mode. The resulting images are then treated with a dedicated stereovision reconstruction algorithm, yielding a full 3-D reconstruction of dislocations arrangement. The success of this method is demonstrated by measurement of dislocation arrangements in two experimental cases.

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References

1- Mott, N. F. Dislocations and the Theory of Solids. Nature 171, 234-237 (1953).

2- Mohammad, S. N. & Morkoc, H. Progress and prospects of group-III nitride semiconductors. Progress in Quantum Electronics 20, 361-525 (1996).

3- Hua, G. C. et al. Microstructure study of a degraded pseudomorphic separate confinement heterostructure blue-green laser diode. Applied Physics Letters 65, 1331-1333 (1994).

4- Midgley, P. A. & Dunin-Borkowski, R. E. Electron tomography and holography in materials science. Nature Materials 8, 271-280 (2009).

5- Agudo Jácome, L., Eggeler, G. & Dlouhý, A. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials. Ultramicroscopy 122, 48-59, d (2012).

6- Barnard, J. S., Eggeman, A. S., Sharp, J., White, T. A. & Midgley, P. A. Dislocation electron tomography and precession electron diffraction – Minimising the effects of dynamical interactions in real and reciprocal space. Philosophical Magazine 90, 4711-4730 (2010).

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