Chemical vapor deposition of heteroepitaxial Si_1-x-yGe _xC_y films on (100)Si substrates

Thin heteroepitaxial films of Si_1-x-yGe_xC_y have been grown on (100)Si substrates using atmospheric pressure chemical vapor deposition at 625°C. The crystallinity, composition, and microstructure of the SiGeC films were characterized using Rutherford backscattering spectrometry, secondary-ion-mass spectrometry, and cross-sectional transmission electron microscopy. The crystallinity of the films was very sensitive to the flow rate of C₂H₄ which served as the C source. Films with up to 2% C were epitaxial with good crystallinity and very few interfacial defects. Between 800 and 900 sccm of 10% C₂H₄ in He, the C content increased dramatically from 2% to 10% and the as-grown films changed from crystalline to amorphous. In order to establish deposition conditions for the crystalline-amorphous phase transformation, one SiGeC film was deposited as the 10% C₂H₄ flow was increased linearly from 500 to 1500 sccm during growth. When the C content reached ∼4%, the film developed considerable stacking defects and disorder, and at around 11% C, the film became amorphous.