LabAdviser/314/Microscopy 314-307/SEM/Nova/Transmission Kikuchi diffraction: Difference between revisions
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Moving the detector from a high-angle to the on-axis position permits to reduce the probe current and size to record a solvable pattern. Kikuchi patterns are more intense at small scattering angles (i.e., near the direction of the optical axis) than at higher angles. Therefore, the intensity of the incident electron beam, and thus the probe size needed to record a solvable pattern is smaller when the detector is moved from a high-angle to the on-axis position. The probe size in combination with the beam broadening affect the total interaction volume, and the width of the interaction volume is directly linked to the lateral resolution. All the experiments and results presented in the next section were obtained using the on-axis detector configuration, which has already become the standard geometry for TKD measurements. | Moving the detector from a high-angle to the on-axis position permits to reduce the probe current and size to record a solvable pattern. Kikuchi patterns are more intense at small scattering angles (i.e., near the direction of the optical axis) than at higher angles. Therefore, the intensity of the incident electron beam, and thus the probe size needed to record a solvable pattern is smaller when the detector is moved from a high-angle to the on-axis position. The probe size in combination with the beam broadening affect the total interaction volume, and the width of the interaction volume is directly linked to the lateral resolution. All the experiments and results presented in the next section were obtained using the on-axis detector configuration, which has already become the standard geometry for TKD measurements. | ||
= In-situ heating TKD analysis of ultra-thin metal fi�lms = | = In-situ heating TKD analysis of ultra-thin metal films = | ||
In this section, the in-situ and high temperatures capabilities of TKD for the analysis of metal thin-�films are presented. The model example chosen for this analysis is the solid-state dewetting of Au thin-�films. Solid-state dewetting is a morphological evolution by which an initially continuous thin �film on an inert substrate turns into a discontinuous array of isolated islands, as sketched in Fig. 8. | |||
This happens because thin �films are kinetically frozen unstable structures as a consequence of their formation far from equilibrium. Since the driving force for dewetting is the minimization of the total energy of the free surfaces of the �film and substrate and of the �film-substrate interface, the total free energy associated with the interfaces of a �film is reduced if the �film agglomerates to form islands. Solid-state dewetting occurs at temperatures well below the melting temperature of the �film, so that the material remains in the solid state throughout the process. Since the rate of dewetting is higher in thinner fi�lms, the temperature at which dewetting occurs decreases with decreasing �film thickness. | |||
== In-situ heating TKD analysis of ultra-thin metal films == | |||