Surface composition of CVD-grown α-SiC layers — an XPS and LEED study

The influence of gas composition during the final process step (i.e. cooling the sample from process temperature to room temperature) of SiC low pressure chemical vapour deposition on structure and composition of the surfaces of homoepitaxially grown α-SiC(0001) layers was studied by means of X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED). Depending on the gas mixture either poorly ordered carbon-rich or silicon-rich surfaces could be observed. After cooling in vacuum or inert gas we found an epitaxial graphite layer on the samples. Only cooling in pure hydrogen ensured the formation of a well-ordered and stoichiometric α-SiC(0001) surface