Mounded Surfaces

In recent years, research interest has turned to understanding the dynamics of more complicated growth mechanisms that are characteristically nonlocal in nature. These investigations have been motivated by experimental results under certain types of deposition techniques including sputter deposition and chemical vapor deposition, most notably the measurement of growth exponents α, β, and z that are not consistent with the predictions of local growth models [8, 22, 35, 103, 143, 160, 185]. This is most evidently seen through an analysis of various values of the growth exponent β that have been reported in the literature for these deposition techniques, as shown in Fig. 4.1. In this figure, the spread of the majority of experimentally reported results is represented with a rectangle for each deposition technique, including thermal evaporation, sputter deposition, chemical vapor deposition, and oblique angle deposition. Most local models predict a relatively small value for β, as represented by the small spread of β for local models, which is evident from Table 3.1. Clearly, local models are not able to explain many of the experimental measurements of β. To explain these results, the theory of surface growth must be amended to include effects that can lead to such a wide range of experimental measurements, which invites the introduction of mounded surfaces.