Grain size Fig. 12 shows a noticeable difference among anatase peaks, , in terms of intensity and bandwidth. This is due to the different grain size within the thin film. The grain size gives a rough measurement on the structural morphology and degree of order inside a crystal. With smaller grain size, there are more crystallites that may take various orientation, and result in broadening the angle of diffraction and decreasing the intensity in an XRD pattern. Similar effect can be seen with very thin TiO2 films, where the amount of crystalline planes satisfying Bragg condition is limited. For a single crystal thin film, the measurements for grain size reveals the thin film thickness. In this subsection, the grain size for TiO2 in each of the sample is calculated using two different ways and compared: first one is by Scherrer equation, and the second one is by simulation with the model described in section 3. The Scherrer equation takes the form: (4.1) stands for the grain size, is the Scherrer constant that can treated as equal to 0.9, λ is incident wavelength that equals to 0.15418 nm and (in rad) is the FWHM of the peak. In order to obtain the grain size from the simulation, the procedure is to find the value of repetition number N which gives the best matching to both peak intensity and FWHM. The results for simulation using different repetition number are plotted in Figs. For PTS0217 sample, N=3 gives the best matching. For the other two samples, there is one additional difficulty as the FWHM value obtained from the model can be
Grain size Fig. 12 shows a noticeable difference among anatase peaks, , in terms of intensity and bandwidth. This is due to the different grain size within the thin film. The grain size gives a rough measurement on the structural morphology and degree of order inside a crystal. With smaller grain size, there are more crystallites that may take various orientation, and result in broadening the angle of diffraction and decreasing the intensity in an XRD pattern. Similar effect can be seen with very thin TiO2 films, where the amount of crystalline planes satisfying Bragg condition is limited. For a single crystal thin film, the measurements for grain size reveals the thin film thickness. In this subsection, the grain size for TiO2 in each of the sample is calculated using two different ways and compared: first one is by Scherrer equation, and the second one is by simulation with the model described in section 3. The Scherrer equation takes the form: (4.1) stands for the grain size, is the Scherrer constant that can treated as equal to 0.9, λ is incident wavelength that equals to 0.15418 nm and (in rad) is the FWHM of the peak. In order to obtain the grain size from the simulation, the procedure is to find the value of repetition number N which gives the best matching to both peak intensity and FWHM. The results for simulation using different repetition number are plotted in Figs. For PTS0217 sample, N=3 gives the best matching. For the other two samples, there is one additional difficulty as the FWHM value obtained from the model can be
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