CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

Abstract

The paper is concerned with chemical vapor deposition in hot wall reactors and in particular with the interaction of homogeneous gas-phase and heterogeneous surface reactions. Based on model considerations it is shown that this interaction has a tremendous influence on the deposition chemistry and kinetics in all cases in which the precursor gas undergoes complex gas-phase reactions. The decisive parameter determining the interaction is given by the ratio of free volume of the deposition space and size of the surface area of the substrate; it is termed the “third parameter” of chemical vapor deposition. Predictions from the model are experimentally confirmed using results on chemical vapor deposition of pyrolytic carbon from methane. The importance of this “third parameter” of chemical vapor deposition in investigations of kinetics and for technical processes of chemical vapor deposition and infiltration is discussed in the conclusion.