Abstract
The structure and composition of SiC nanolayers are comprehensively studied by X-ray reflectometry, IR-spectroscopy, and atomic-force microscopy (AFM) methods for the first time. SiC films were synthesized by the new method of topochemical substitution of substrate atoms at various temperatures and pressure of CO active gas on the surface of high-resistivity low-dislocation single-crystal n-type silicon (111). Based on an analysis and generalization of experimental data obtained using X-ray reflectometry, IR spectroscopy, and AFM methods, a structural model of SiC films on Si was proposed. According to this model, silicon carbide film consists of a number of layers parallel to the substrate, reminiscent of a layer cake. The composition and thickness of each layer entering the film structure is experimentally determined. It was found that all samples contain superstoichiometric carbon; however, its structure is significantly different for the samples synthesized at temperatures of 1250 and 1330°C, respectively. In the former case, the film surface is saturated with silicon vacancies and carbon in the structurally loose form reminiscent of HOPG carbon. In the films grown at 1330°C, carbon is in a dense structure with a close-to-diamond density.