LabAdviser/314/Microscopy 314-307/SEM/Nova/Transmission Kikuchi diffraction: Difference between revisions
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growth, and the hole continues to grow in directions where grains along the hole edge have a higher interface energy with the substrate. This expansion only stops when the hole becomes completely sorrounded by low-interface energy grains, as in the case of Fig. 8 and 9. | growth, and the hole continues to grow in directions where grains along the hole edge have a higher interface energy with the substrate. This expansion only stops when the hole becomes completely sorrounded by low-interface energy grains, as in the case of Fig. 8 and 9. | ||
Since TKD measurements provided a large amount of data for each scanned point in the map (54000 total acquired points at the step size of 10 nm), statistically significant quantitative data analysis could be performed from this series of measurements. The two classes of grains already observed in Fig. 9 were analyzed, defined as i) PO-grains with [111]//growth direction (using tolerance angle of 15°) and ii) non-PO grains with other orientations. The average grain size evolution of both classes of grains is shown in Fig. 10a for annealing temperatures up to 600°C. | Since TKD measurements provided a large amount of data for each scanned point in the map (54000 total acquired points at the step size of 10 nm), statistically significant quantitative data analysis could be performed from this series of measurements. The two classes of grains already observed in Fig. 8 and 9 were analyzed, defined as i) PO-grains with [111]//growth direction (using tolerance angle of 15°) and ii) non-PO grains with other orientations. The average grain size evolution of both classes of grains is shown in Fig. 10a for annealing temperatures up to 600°C. | ||
The graph confirms the trend from the maps shown in Fig. 8, revealing that grain growth started already at 120°C. The PO grains were larger than the non-PO ones already from the starting nanostructure and grew considerably faster: by a temperature of 220°C, PO grains have almost triplicated their average size, while non-PO grains maintained their average size of 33 nm. Furthermore, up to 550°C practically only the PO grains grew. Fig. 10b shows the evolution of the number of indexed points for the two classes of grains, while Fig. 10c shows the number of grains of each class during annealing. The data shows that the fraction of indexed points and the number of non-PO grains started to decrease at the annealing temperature of 150°C. Considering that the holes were formed near non-PO grains as described above, the decrease of non-PO indexed points can be considered as a signal of hole formation in the film, even if holes are not visible in the image at that temperature. For PO grains, the fraction of indexed points kept increasing up to 350°C, while the number of grains already started to decrease at 180°C, indicating that such grains kept growing and coalescing before the dewetting process took place. | The graph confirms the trend from the maps shown in Fig. 8, revealing that grain growth started already at 120°C. The PO grains were larger than the non-PO ones already from the starting nanostructure and grew considerably faster: by a temperature of 220°C, PO grains have almost triplicated their average size, while non-PO grains maintained their average size of 33 nm. Furthermore, up to 550°C practically only the PO grains grew. Fig. 10b shows the evolution of the number of indexed points for the two classes of grains, while Fig. 10c shows the number of grains of each class during annealing. The data shows that the fraction of indexed points and the number of non-PO grains started to decrease at the annealing temperature of 150°C. Considering that the holes were formed near non-PO grains as described above, the decrease of non-PO indexed points can be considered as a signal of hole formation in the film, even if holes are not visible in the image at that temperature. For PO grains, the fraction of indexed points kept increasing up to 350°C, while the number of grains already started to decrease at 180°C, indicating that such grains kept growing and coalescing before the dewetting process took place. | ||