The hole effective mass in a compressively strained Si formed on a (100) surface is expected to be low. The growth of a high quality strain-relaxed Si1-xCx increases the possibility of high performance electronic devices using compressively strained Si film. In this study, growth conditions and their influence on microstructural aspects of Si1-xCx grown by gas-source molecular beam epitaxy were studied. Disilane and trimethylsilane were used as source gases. It was found that the strain-relaxation process and defect formation were influenced not only by substrate temperature but also by flow rates of the source gases. Relationships between the morphological aspects and non-substitutional carbon concentration were studied. (c) 2013 Elsevier B.V. All rights reserved.