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Correlative micro-diffraction and differential phase contrast study of mean inner potential and subtle beam-specimen
Mingjian Wu1, Erdmann Spiecker1
1Institute of Micro- and Nanostructure Research & Center for Nanoanalysis and Electron Microscopy (CENEM), Department of Materials Science, Universität Erlangen-Nürnberg, Cauerstraße 6, D-91058 Erlangen, Germany.
Ultramicroscopy
|April 4, 2017
Summary
We measured the mean inner potential (MIP) of silicon and gallium arsenide using electron microscopy. Subtle Fresnel fringe displacements reveal potential differences in beam-sensitive samples.
Area of Science:
- Materials Science
- Solid-State Physics
- Electron Microscopy
Background:
- Accurate determination of the mean inner potential (MIP) is crucial for quantitative analysis in transmission electron microscopy.
- Understanding beam-specimen interactions, especially at sample edges, is essential for precise measurements.
- Differential phase contrast (DPC) and micro-diffraction are powerful techniques for probing electrostatic potentials.
Purpose of the Study:
- To determine the mean inner potential (MIP) of silicon (Si) and gallium arsenide (GaAs) using correlative micro-diffraction and DPC-STEM.
- To investigate the origin of subtle beam-specimen interactions at the edges of wedge-shaped crystals.
- To evaluate the potential for using Fresnel fringe displacements for contactless probing of weak potential differences.
Main Methods:
- Correlative micro-diffraction and DPC-STEM experiments on wedge-shaped Si and GaAs crystals.
- Numerical simulations to model beam-specimen interactions and Fresnel fringe formation.
- Direct evaluation of beam refraction in micro-diffraction mode for MIP determination.
Main Results:
- MIP values for Si and GaAs were measured as 12.48 ± 0.22 V and 14.15 ± 0.22 V, respectively.
- DPC-STEM measurements yielded highly consistent MIP values.
- Experimental observation and numerical simulation of Fresnel fringes showed perfect agreement regarding fringe displacements near the sample edge.
Conclusions:
- The study successfully determined the MIP of Si and GaAs with high accuracy.
- Subtle Fresnel fringe displacements near sample edges can be quantitatively analyzed.
- This method offers a potential route for pseudo-contactless probing of weak potential differences in beam-sensitive materials.
