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electron microscopy(FE-SEM) and an atomic force microscopy(AFM). The domain and crosssectional view were examined by transmission electron microscopy(TEM). RESULTS AND DISCUSSION We previously reported that (111 )-oriented PbTiO 3 thin films formed triangular islands at initial growth stage and exhibited two-dimensional growth[9]. There are two reasons why (111)oriented PbTiO 3 islands were used in this study. One is that (11 1)-oriented PbTiO 3 islands enable us to observe the relationship between the lateral size and domain structure because they grow more rapidly in horizontal direction than in vertical direction. The other reason is that it is not necessary to examine the structure and orientation by X-ray diffraction(XRD), because triangular islands directly show that they have (111)-oriented perovskite structure. At first, in order to prepare (111)-oriented PbTiO 3 islands, the Ar carrier gas supply ratio of [Pb]/([Pb]+[Ti]) was optimized. When the [Pb]/([Pb]+[Ti]) ratio was 0.54, highly (111)-oriented PbTiO 3 thin films were grown. The XRD profile of PbTiO 3 film deposited for 20min is shown in Fig. 1.From this result, we prepared PbTiO 3 islands at the [Pb]/([Pb]+[Ti]) ratio of 0.54. Figure 2 shows SEM photomicrographs of PbTiO 3 islands deposited for 1 and 3 min. Triangular PbTiO3 islands were observed and the length of the base of triangular islands increased from 10 to 180nm as the deposition time increased from I to 3min. Figure 3 shows cross-sectional TEM photomicrographs of PbTiO 3 islands deposited for 1 and 3min. Triangular-shaped islands and trapezoidal-shaped islands were observed. PbTiO 3 islands discussed in this section are indicated by arrows in the figures. The height of PbTiO 3 islands increased slightly from 10 to 40nm as the deposition time increased. On the other hand, the length of the base of the triangular or trapezoidal islands increased greatly from 10 to 180nm. These results show that the horizontal growth rate of PbTiO 3 films is much higher than the vertical growth rate. High magnification TEM images of PbTiO 3 islands indicated by arrows in Fig.3 are shown in Fig.4. The dark-contrast lines tilted to the left were observed in each PbTiO 3 island, as shown in Figs.4(a)(c). The lines extended all the way to island surface. In Figs.4(b) and (c), the lattice planes which are normal to the substrate were also observed. They were found to be {110} or {101 }-planes, because the lattice spacing of 0.28nm observed in Figs.4(b) and (c) was approximately same as the

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50 40 20 (deg.) Fig. 1 XRD profile of PbTiO 3 thin films deposited for 20min. 20

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(c)

Fig.3 Cross-sectional TEM photomicrographs of PbTiO'3 islands deposited for (a)l and (b),(c)3min. 323

Fig.4 High magnification TEM images of the PbTiO 3 islands indicated by arrows in Fig.3. d-spacing of(l 10) or (101)-plane of bulk ceramics. However, it was quite difficult to identify these planes whether {110} or {101 }-planes, because the difference between the lattice spacing of (110)324

(a)

(b)

(C)