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The shape of field emitters and the ion trajectories in three‐dimensional atom probes
Author(s) -
F. Vurpillot,
Bostel,
Blavette
Publication year - 1999
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.1999.00637.x
Subject(s) - ion , atom probe , common emitter , atomic physics , field (mathematics) , surface (topology) , atom (system on chip) , resolution (logic) , materials science , distribution (mathematics) , optics , molecular physics , physics , computational physics , geometry , optoelectronics , mathematics , quantum mechanics , artificial intelligence , transmission electron microscopy , computer science , pure mathematics , embedded system , mathematical analysis
The lateral resolution of three‐dimensional atom probes is mainly controlled by the aberrations of the ion trajectories near the specimen surface. For the first time, a simulation program has been developed to reconstruct the ion trajectories near a sharp hemispherical electrode defined at the atomic scale. Surface atoms submitted to the highest field were removed one by one. The consecutive gradual change of the surface topology was taken into account in the calculation of ion trajectories. As the tip was ‘field evaporated’, the initial spherical shape of the emitter was observed to transform gradually into a polygonal shape. When the tip reached its equilibrium shape, the field distribution at the tip surface was found to be much more uniform compared to the initial distribution. The calculated distribution of ion impacts on the detector exhibits the presence of depleted zones both at the centre of low index poles and along <001> zone axes. These predictions are in excellent agreement with experiments.