Texture evolution in rhombohedral boron carbide films grown on 4H-SiC(000) and 4H-SiC(0001) substrates by chemical vapor deposition

Abstract

Boron carbide in its rhombohedral form (r-B_xC), commonly denoted B₄C or B₁₃C₂, is a well-known hard material, but it is also a potential semiconductor material. We deposited r-B_xC by chemical vapor deposition between 1100 °C and 1500 °C from triethylboron in H₂ on 4H-SiC(0001) and 4H-SiC(000). We show, using ToF-ERDA, that pure B₄C was grown at 1300 °C, furthermore, using XRD that graphite forms above 1400 °C. The films deposited above 1300 °C on 4H-SiC(000) were found to be epitaxial, with the epitaxial relationships B₄C(0001)[100]‖4H-SiC(000)[100] obtained from pole figure measurements. In contrast, the films deposited on 4H-SiC(0001) were polycrystalline. We suggest that the difference in growth mode is explained by the difference in the ability of the different surfaces of 4H-SiC to act as carbon sources in the initial stages of the film growth.