A microscopic mechanism of film growth from non-condensed phases

Abstract

A self-consistent kinetic analysis of film growth at the atomic (molecular) level is compared with structural, morphological and thermal kinetic experimental data. A refined model of the surface makes it possible to analyse the formation of defects in films. With the same purpose, the microkinetic equations are transformed and supplemented with a macrokinetic system so that the molecular kinetic analysis can be applied to later stages of nucleation and to layered growth. Excellent agreement of the theory with molecular beam epitaxial experimental data is achieved using “non-classical” values of the activation energies of elementary events. A possible physical meaning of this result is discussed. In the case of vapour phase epitaxy, a dense chemisorption layer on a growing germanium face and the diffusionless ordering mechanism are detected even in the first pilot experiments. A molecular kinetic model based on these observations can be used to predict correctly the conditions of perfect growth of germanium, silicon, GaAs and GaP in homoepitaxial and heteroepitaxial systems. A molecular kinetic theory cannot be developed as an independent domain. However, as a component of a self-consistent “model-experiment” system, it can considerably elaborate on the concepts of the fundamental mechanism of film growth.