Island size distribution

This work is devoted to study the influence of substrate temperature on CrSi2 island size distribution on Si substrate and the effect of Si layer thickness at MBE process on the formation of Si(l 1 l)/CrSi2 NCs/Si(l 11) heterostructures and CrSi2 NC moving in it. 

The samples prepared at 500 °C, 550 °C and at 600 °C by RDE of 0.6 nm Cr without Si cap layer were analyzed by AFM to characterize the CrSi2 nanoislands. Cr deposition at 500 °C silicide islands have bimodal size distribution (10-20 nm and 40-80 nm) as it is shown in Fig. la. The bimodal size distribution indicates that significant secondary nucleation occurs during Cr deposition at 500 C in parallel to the growth of the Islands. At 550 °C a narrow CrSii island size distribution was observed as it is shown in Fig. lb. Islands had the maximal density (4T0 cm ), minimal sizes (15-20 nm) and heights (2-4 nm). The silicon surface is 30-50% covered by nanoislands. 

From scaling analysis of the island size distribution in Figure 4.3.7a, the surface coverage (9) and island density per unit surface (N) for pentacene films with the same nominal thickness of 0.5 nm can be plotted as a function of increasing... 

Amar, J.G., Family, F., and Lam, P.M., Dynamic scaling of the island-size distribution and percolation in a model of submonolayer molecular-beam epitaxy, Phys. Rev. B 50, 8781-8797, 1994. 

Ruiz, R. et al.. Dynamic scaling, island size distribution, and morphology in the aggregation regime of submonolayer pentacene films, Phys. Rev. Lett. 91, 136102, 2003. Pratontep, S. et ah. Correlated growth in ultrathin pentacene films on silicon oxide Effect of deposition rate, Phys. Rev. B 69, 165201, 2004. 

Onr discussion of the free energy driving forces will mostly follow the discussions ontlined in Venables et al. [5] and in Markov [3], The extension of the atomistic approach to the organics will come from Verlaak et al. [15]. The elements of the rate equation will follow Venables et al. [5]. Dynamic scaling will then follow as an extension to the rate equations coupled with some assumptions about the island size distributions [23]. For deposition beyond the first layer the comparison of model predictions with experiment will follow Cohen et al. [29]. The height-height correlation description will follow Krim and Palasantzas [30]. 

The temperature dependence of the critical island size for pentacene on Si02 was explored by Tejima et al. [44] and the results are displayed in Figure 5.1.11. The same scaled island size distributions are shown in Figure 5.1.11a for four different substrate temperatures at a constant thickness of -0.2 ML. The curves corresponding to critical island sizes of one, two, and three are shown and it is clear that the different substrate temperatures used result in different critical island sizes. The scaled island densities for thick pentacene layers are plotted as a function of... 

Tejima, M., Kita, K., Kuno, K., and Toriumi, A., Study on the growth mechanism of pentacene thin films by the analysis of island density and island size distribution, Appl. Phys. Lett., 85, 3746, 2004. 

Fig. 58. Confinement nucleation of adatom islands on a dislocation network, (a) Ordered (25 X 25) dislocation network formed by the second Ag monolayer on Pt( 111) on deposition at 400 K and subsequent annealing to 800 K. The inset shows a model of this trigonal strain relief pattern, (b) A superlattice of islands is formed on Ag deposition onto this network at 110 K (coverage = 0.10 monolayers). The inset shows the Fourier transform of the STM image, (c) Island size distributions for random and ordered nucleation. The curve for ordered nucleation is a binominal fit. The curve labeled i = 1 shows the size distribution from scaling theory for random nucleation on an isotropic substrate. Size distributions were normalized according to scaling theory (5 is the island size in atoms, (S) its mean value, and Ns the density of islands with size s per substrate atom), (d) Zoom into image (b) [198]. Reprinted with permission from H. Brune et al.. Nature 344, 451 (1998), 1998, Macmillan Magazines Ltd.

Kori distribution was proposed to estimate the island size distribution of the archipelago by the concept of fractals. It has demonstrated that the islands distribution satisfy the Kor6 distribution ... 

Figure 5. Morphology and particle size distribution of an island silver thin film deposited on native oxide covered silicon (a) before ion bombardment and after (b) 0.5 keV Ar sputtering with 1.1 X 10, (c) 2.5 X 10, and (d) 3.9 x 10 ion/cm dose. Sputtering speed for silver was around 3-4ML/min. Total elapsed sputtering time is indicated on each size distribution graphs. (Reprinted from Ref [123], 2003, with permission from Springer.)...

SEM studies of as-deposited AlSb films revealed the formation of smooth films. No island growth was detected. In addition, the presence of both single and agglomerated crystallites with particle sizes ranging from 300 to 700 nm as is illustrated in Fig. 47 was confirmed. The size distribution was found to be almost independent of the deposition temperature. 

Figure 9.35 shows a typical set of mass size distributions for total suspended particles (TSP), Na, Cl, Al, V, NO-, S04, and NH4 at Chichi in the Ogasawara (Bonin) Islands, about 1000 km southeast of the main island of Japan (Yoshizumi and Asakuno, 1986). As expected for a marine site such as this, Na and Cl from sea salt predominate, and both the TSP and Na and Cl components peak in the coarse particle range. Al is also found primarily in the larger particles and is attributed to a contribution from soil dust. On the other hand, vanadium, non-sea salt sulfate (nss-S04 ), and ammonium are primarily in the fine particles. The vanadium levels are extremely low and likely reflect long-range transport of an air mass containing the products of combustion of fuel oil, which contains V because it is likely associated with a combustion source, it would be expected in the fine particle mode, consistent with Fig. 9.35. 

FIGURE 9.35 Observed size distributions of total suspended particles and some of the inorganic constituents of airborne particles at Chichi, Ogasawara Islands, Japan, in 1983 (adapted from Yoshizumi and Asakuno, 1986). 

Table 3.2 shows the influence of the initial PEI concentration on the resulting particle size distribution. Both the size and the number of PEI domains increased in the sea-island morphology, whereas the size of thermoset nodule decreased and the number of nodules increased in the nodular morphology as the initial PEI concentration was increased. 

At the Mediterranean station Finokalia (FKL) located in the Greek island of Crete, the particle number size distributions were bimodal for winter with an Aitken mode around 50 nm particle diameter and accumulation mode at 150 nm. The spring and summer were dominated by strong accumulation mode at around 100 nm. 

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