Structural particularities of carbon-incorporated Si-Ge heterostructures

The structural consequences of carbon incorporation into silicon and Si-Ge layers deposited on silicon (100) by rapid thermal chemical vapor deposition have been studied. High resolution X-ray diffraction (HRXRD) analysis, channeling Rutherford backscattering spectroscopy (RBS), Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) have been used to discover the structural particuliarities of this material in relation to the temperature of deposition. Experimental elastic energy density measurements have been compared with theoretical predictions for germanium concentrations of 0%, 10% and 16% as a function of substitutional carbon content. Raman spectroscopy measurements compared with an original high resolution transmission electron microscopy treatment showed that local compressive and tensile zones can simultaneously coexist at the interface. These localized tensile zones could probably act as pinning centers, blocking the propagation of dislocations, and hence increasing the critical thicknesses. With unadapted growth conditions, carbon segregation can occur. This effect can enhance local strain variations.