Ethylene C2H4 for Si1-x-yGexCy films by APCVD
Ethylene C2H4 has been applied as carbon source for the deposition of thin heteroepitaxial films of Si1-x-yGexCy on Si(100) substrates at 625 °C using atmospheric pressure CVD. The crystallinity, composition, and microstructure of the SiGeC films were characterized using RBS, SIMS, XTEM. The crystallinity of the films was very sensitive to the flow rate of C2H4, i.e. carbon content in the solid. Films with up to 2% C were epitaxial with good crystallinity and very few interfacial defects. At higher ethylene flow (from 800 to 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 study transition from crystalline to amorphous phase in detail, one SiGeC film was grown with ramping linearly the 10% C2H4 flow 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. [[i]]
[i]Atzmon, Z., Bair, A. E.; Jaquez, E. J. ; Mayer, J. W. ; Chandrasekhar, D. ; Smith, David J. ; Hervig, R. L.; Robinson, McD., Applied Physics Letters, Vol.65 , Iss.: 20, p.2559 - 2561 , “Chemical vapor deposition of heteroepitaxial Si1-x-yGexCy films on (100)Si substrates