SEM secondary electron images of the ZnO initial layer deposited by PLD (sample a), PLD and hydrothermal growth (sample b), and PLD plus CVD (sample c). Cross-sectional SEM images have been present elsewhere (Ref. 6).
(a) (0002) Two-beam bright field image of PLD grown template (sample a) revealing nanorods that appear to be defect-free. (b) Thinner region of the same sample showing a high density of TDs within the buffer layer. (c) Thick PLD layer (sample d) showing TDs propagating through the whole film. The scale bars are 100 nm.
The (0002) two-beam bright field image of ZnO grown hydrothermally on a PLD layer (sample b). The sample was prepared by FIB milling. The scale bar is 100 nm.
(0002) Two-beam bright field image of the hydrothermal growth on PLD made template taken along . The sample was prepared by FIB milling. Dislocations (for example, at A) illustrate the misorientation of subgrains.
(a) and (b) show two-beam bright field images of a CVD treated PLD template (sample d) in and reflections, respectively. Both images came from the same area, marked by the hemisphere precipitate in the left. Scale bar is 200 nm.
CBED experimental patterns (on left) taken on (a) sample d and (b) sample c along of ZnO, respectively. The upper spot represents the growth direction of the film. The simulations (right) are many beam calculations using the JEMS software, using thicknesses of 91 nm for (a) and 118 nm for (b) for the best fit to the experimental results.
The total TD density at different depths. indicates the total thickness of three continuous films, i.e., samples b– d.
A bright field TEM image of sample b showing the nanorod originating from the ZnO/sapphire interface. The nanorod has expanded both laterally and vertically, leaving a gap between the nanorod and buffer layer distinguished by a white line contrast. The scale bar is 100 nm.
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