Polarity determination and control of SiC grown on Si

The polarity of the 3C–SiC epitaxial layers grown on 3C–SiC(1 1 1)/Si(1 1 1) pseudosubstrates formed by carbonization using the deposition of elemental carbon under ultra-high vacuum conditions and alternatively at atmospheric pressure in a rapid thermal chemical vapour deposition reactor were studied with different diffraction and electron spectroscopy methods. It is unambiguously shown that the conversion under CVD conditions and the chosen heating-up rate led to the formation of C-face 3C–SiC(1¯ 1¯ 1¯), where as for lower heating-up rates and carbon fluxes Si-face 3C–SiC(1 1 1) was obtained. The crystallographic polarity of the carbonized layers is then reproduced during epitaxial growth. Comparing the measurement results of different techniques available to detect the absolute crystallographic orientation it is shown that X-ray diffraction can be used routinely for the determination of the crystallographic polarity, even if the layers are much thinner then the penetration depth of the X-ray radiation. A model, which is based on the formation of energetically or kinetically favoured surface reconstructions at the early stages of the Si to SiC conversion process, is proposed to explain the formation of the different crystallographic polarities of 3C–SiC on a nonpolar Si(1 1 1) substrate.