Figure 3 shows the survey XPS spectra of the deposited Pt samples corresponding to different pulse times of (MeCp)Pt(Me)3 in the case of 70 deposition cycles. It is seen that the intensity ratio of Pt 4p 3/2 to O 1s peaks increases distinctly with an increase of the (MeCp)Pt(Me)3 pulse time from 0.25 s to 1.5 s. This reflects a marked increase

this website of Pt coverage on the surface of the Al2O3 film. When the pulse time is further increased to 2 s, the aforementioned intensity ratio exhibits a slight increase. Meanwhile, it is observed that the peaks of Pt 4d exhibit remarkable enhancement in comparison with those corresponding to 1.5-s pulse time. This indicates that when the pulse time exceeds 1.5 s, see more the Pt deposition is dominated by its growth on the surface of Pt AR-13324 nanodots due to the fact that most of the Al2O3 surface has been covered by ALD Pt, thus likely leading to the preferential vertical growth of

Pt. Figure 3 Survey XPS spectra of ALD Pt on Al 2 O 3 film as a function of (MeCp)Pt(Me) 3 pulse time. Substrate temperature 300°C, deposition cycles 70. Figure 4 shows the surface SEM images of the deposited Pt nanodots corresponding to different pulse times of (MeCp)Pt(Me)3 respectively. In the case of 0.25-s pulse time, the resulting Pt nanodots are very small, sparse, and nonuniform. Nevertheless, when the pulse time increases to 0.5 s, the resulting Pt nanodots become much denser and bigger, thus revealing that the pulse time of (MeCp)Pt(Me)3 plays a key role in the growth of Pt nanodots. Further, as the pulse time increases gradually Cell press to 2 s, the resulting Pt nanodots do not exhibit distinct changes based on the SEM images, but it is believed that the distances between nanodots become narrower and narrower, and even the coalescence between adjacent nanodots could occur. Therefore, to ensure the

growth of high-density Pt nanodots, the coalescence between adjacent nanodots should be avoided during ALD. For this purpose, the pulse time of (MeCp)Pt(Me)3 should be controlled between 0.5 and 1 s. Figure 4 SEM images of ALD Pt on Al 2 O 3 for different pulse times of (MeCp)Pt(Me) 3 . (a) 0.25, (b) 0.5, (c) 1, and (d) 2 s (substrate temperature 300°C, deposition cycles 70). Influence of deposition cycles on ALD Pt Figure 5 illustrates the surface morphologies of the resulting Pt nanodots as a function of deposition cycles. In the case of ≤60 deposition cycles, the deposited Pt nanodots exhibit low densities and small dimensions. When the number of deposition cycles increases to 70, the density of Pt nanodots increases remarkably. As the deposition duration reaches 90 cycles, the resulting Pt nanodots exhibit much larger dimensions and irregular shapes as well as a reduced density. Figure 5 SEM images of ALD Pt on Al 2 O 3 as a function of deposition cycles. (a) 40, (b) 60, (c) 70, and (d) 90 cycles. Substrate temperature, 300°C; pulse time of (MeCp)Pt(Me)3, 1 s.