Island growth

Not only do the new and old surfaces produce surface plasmons in the island-growth mode, but the interlace between the growing film and the substrate is also capable of producing an interphase plasmon excitation. Typically an interphase plasmon will appear at an energy intermediate between the surface plasmons of the two phases. Its intensity will grow as the island phase grows laterally but will eventually disappear as the interface retreats below the thickening island layer. 

A. Hopkinson, J. M. Bradley, X.-C. Guo, D. A. King, Nonlinear island growth dynamics in adsorbate-induced restructuring of quasihexagonal reconstructed Pt(lOO) by CO. Phys Rev Lett 77 1597-1600, 1993. 

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. 

The kinetics of CO oxidation from HClOi, solutions on the (100), (111) and (311) single crystal planes of platinum has been investigated. Electrochemical oxidation of CO involves a surface reaction between adsorbed CO molecules and a surface oxide of Pt. To determine the rate of this reaction the electrode was first covered by a monolayer of CO and subsequently exposed to anodic potentials at which Pt oxide is formed. Under these conditions the rate of CO oxidation is controlled by the rate of nucleation and growth of the oxide islands in the CO monolayer. By combination of the single and double potential step techniques the rates of the nucleation and the island growth have been determined independently. The results show that the rate of the two processes significantly depend on the crystallography of the Pt surfaces. 

The changes in the transient shapes reflect Changes in the reaction mechanism. At low potentials, the reaction is controlled simultaneously by the rate of nucleation and the growth of the oxide islands, at high potentials the reaction is controlled by the rate of the island growth. 

On highly ordered pyrolytic graphite, HOPG(OOOl) electrodes, no UPD has been detected owing to weak carbon-lead interactions [311]. Deposition occurs by three-dimensional island growth according to Volmer-Weber mechanism. Initial steps are controlled by progressive nucleation on active sites and hemispherical diffusion. 

To integrate eqn. (15), one needs expressions for u and i. Let us first consider the island growth rate, u. 

Cao, C59N [82] Initial adsorption at dangling bonds, then at higher coverage molecule-molecule interactions dominate with island growth. An insight to the molecule-molecule interaction can be gained. 

Island growth also occurs with polycrystalline films, but in epitaxy, the islands combine to form a continuous single-crystal film, that is, one with no grain boundaries. In reality, nucleation is much more complex in the case of heteroepitaxy. Nucleation errors may result in relatively large areas, or domains, with different crystallographic orientations. The interfaces between domains are regions of structural mismatch called subgrain boundaries and will be visible in the microstructure. 

Fig. 2.8. Trajectories of the dielectric function obtained by In situ ellipse-metry during growth of a-Si H. The predicted trajectories are shown for uniform growth (dashed) and island growth (solid) (Collins and Cavese 1989).

---