A model of submonolayer epitaxial growth mediated by a monolayer of surfactant is studied, where exchange of adatoms with their underneath surfactant atoms is reversible; i.e., an exchanged adatom can reexchange with the lifted surfactant atom to return to the top of the surfactant layer when the substrate temperature is high enough. A rate equation analysis shows that island nucleation governed by the reexchanging-controlled surface diffusion obeys a scaling law, which connects the nucleation density with the rates of the deposition, surface diffusion, exchange, and reexchange process. Our model system reveals distinct nucleation transitions due to the activated exchange and reexchange, and the nucleation density as a function of temperature exhibits a characteristic N shape with a minimum and a maximum, which define the transition temperatures. The analytical results are confirmed by comparison with kinetic Monte Carlo simulations.

A helical cellular automata (HCA) model constructed on a two-dimensional grid of cells with a helical structure is presented and the pattern formation of this model studied by numerous computer simulations. It is found that the evolutions of the HCA are sensitive to the circumference of the helix p. With various p, the initial growth of the model generates various patterns ranging from Sierpinski triangle gasket, complex textured pattern, to lateral quasiperiodic structure. A sudden transition from regular fractal to compact pattern occurs near the point where p is equal to a positive integer power of 2. With increasing height of the patterns (increasing growth time), the model also exhibits different growth behaviors in the vertical direction for various p, including the formation of regular periodic patterns and the evolution from initial regular patterns to eventual random structures. Fractal dimension analysis is used to characterize these different evolution processes quantitatively.

High-accuracy inductor model is vital for the success of RF/mm-wave circuit design. In this article, the development of two-p scalable model with four ladder skin effect structure has been described in detail. For the scalable compact circuit modeling, a set of formulas by which all of the compact circuit elements can be calculated according to the components geometric dimensions and process parameters will be given. The proposed modeling method is regarded as full scalable as all the component parameters are calculated by physical equations or revise equations. A series of spiral inductors with various geometries have been fabricated with 0.13 lm SiGe BiCMOS aluminum process to verify the model. Excellent agreements are obtained between the measured data and calculation form the proposed model up to frequencies above self-resonant. This scalable 28-element two-p model enables to accurately characterize RF behaviors of on-chip spiral inductors and optimize the inductor performance. V C 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:93-100, 2015.