Dimer strings, anisotropic growth, and persistent layer-by-layer epitaxy

Epitaxial growth and the art of computer simulations

The results of kinetic simulations of the aggregates formed during the deposition of atoms on a semiconductor surface are reviewed. Because the kinetic parameters are poorly known and the accuracy of the existing interatomic potentials has not been sufficiently tested, the goal has been to reach a qualitative understanding of the formation of unusual patterns during growth, such as the segregation of aluminum during the growth of aluminum-gallium-arsenide (AlGaAs) coherent tilted superlattices and the formation of thin, long, and parallel islands during the deposition of Si on an Si(100) surface. Kinetic mechanisms for these phenomena are proposed.

Adatom pairing structures for Ge on si(100): the initial stage of island formation

With the use of scanning tunneling microscopy, it is shown that germanium atoms adsorbed on the (100) surface of silicon near room temperature form chainlike structures that are tilted from the substrate dimer bond direction and that consist of two-atom units arranged in adjoining substrate troughs. These units are distinctly different from surface dimers. They may provide the link missing in our understanding of the elementary processes in epitaxial film growth: the step between monomer adsorption and the initial formation of two-dimensional growth islands.

AN ATOMISTIC VIEW OF Si(001) HOMOEPITAXY

▪ Abstract  Growth of thin films from atoms deposited from the gas phase is intrinsically a non-equilibrium phenomenon dictated by a competition between kinetics and thermodynamics. Precise control of the growth becomes possible only after achieving an understanding of this competition. In this review, we present an atomistic view of the various kinetic aspects in a model system, the epitaxy of Si on Si(001), as revealed by scanning tunneling microscopy and total-energy calculations. Fundamentally important issues investigated include adsorption dynamics and energetics, adatom diffusion, nucleation, sticking, and detachment. We also briefly discuss the inverse process of growth, removal by sputtering or etching. We aim our discussions to an understanding at a quantitative level whenever possible.