For a systematic investigation, the Au film thickness (thickness) was carefully varied while fixing the other growth parameters. As clearly shown in the cross-sectional line profile in Selleck Avapritinib Figure 1(b-1), the surface was atomically smooth even after the Au deposition. The surface morphologies by a systematic annealing process are shown with AZD5582 clinical trial 2 nm thickness in Figure 1c and 9 nm thicknesses in Figure 1d. Under an identical growth condition, the self-assembled Au droplets showed significant
distinction in the size and density distribution depending on the thickness. Figure 2 shows the detailed evolution process of the self-assembled Au droplets on GaAs (111)A with the thickness variation between 2 and 20 nm. AFM top views of 3 × 3 μm2 are shown in Figure 2a,b,c,d,e,f,g,h, and those of 1 × 1 μm2 are shown in Figure 2(a-1) to (h-1). Figure 3a,b,c,d,e,f,g,h shows the cross-sectional
surface line profiles acquired from the 1 × 1-μm2 AFM images in Figure 2(a-1) to (h-1) indicated with white lines. FFT power spectra are shown in Figure 3(a-1) to (h-1). Figure 4 summarizes the average height (AH), average density (AD), and lateral diameter (LD) of the self-assembled PI3K Inhibitor Library concentration Au droplets on GaAs (111)A compared to the various thicknesses. The root mean squared (RMS) roughness (R q) values of samples are summarized in Figure 4d. In general, the average size including height and diameter of the self-assembled Au droplets on GaAs (111)A was gradually increased with the increased thicknesses as clearly shown in the AFM images in Figure 2 and the surface line profiles in Figure 3 as well as the summary plots in Figure 4a,c. Meanwhile, the density of Au droplets was gradually decreased as clearly seen in Figures 2 and 4b. For example, with 2 nm Au deposition, the very densely packed dome-shaped Au droplets were formed on GaAs (111)A as presented in Figure 2a and (a-1) with the AD of 4.23 × 1010 cm−2. The corresponding
AH was 23 nm and the LD was 52.5 nm as shown in Figure 4a,c. At 2.5 nm thickness, the size of droplets grew larger and the density was reduced as clearly shown in Figure 2b and (b-1): the AH was increased by × 1.4 to 32.3 nm and the LD increased by × 1.8 to 94.4 nm as shown BCKDHB in Figure 4a,c. On the other hand, as shown in Figure 4b, the AD decreased by × 3.41 to 1.24 × 1010 cm−2. With relatively lower coverage of 2 and 2.5 nm thicknesses, the Au droplets were quite round and uniformly distributed over the surface, as shown in the AFM images of Figure 2a,b. With 3 nm thickness, the Au droplets were also quite uniformly distributed over the surface and began to show a slight elongation as shown in the AFM images in Figure 2c. Similarly, with the further increase of thicknesses between 4 and 20 nm, the continuous decrease in density with the associated increase in size was clearly observed as shown in Figures 2,3,4. Overall, the size of Au droplets was increased by × 4.