Substitutional C fraction and the influence of C on Si dimer diffusion in Si1−yCy alloys grown on (001) and (118) Si

• Published in: Applied physics letters 2000-08, Vol.77 (9), p.1310-1312
• Main Authors: Croke, E. T., Grosse, F., Vajo, J. J., Gyure, M. F., Floyd, M., Smith, David J.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.1287728

The dependence of substitutional C fraction on growth temperature and substrate orientation is measured for Si1−yCy alloy films grown on (001) and (118) Si by molecular-beam epitaxy. Secondary ion mass spectrometry and high-resolution x-ray diffraction were used to measure the total C and the substitutional C concentrations, respectively, in several samples prepared at temperatures between 450 and 650 °C. The substitutional C fraction decreased rapidly with increasing temperature in this range, regardless of orientation, and was slightly lower for growth on (118) Si. Cross-sectional transmission electron microscopy on (118)-oriented samples revealed a tendency for C to concentrate periodically on (001) facets which formed immediately after initiation of Si1−yCy growth. A kinetic Monte Carlo simulation based upon enhanced diffusion of Si dimers in the presence of subsurface C predicted a step instability leading to step bunching and the formation of periodic surface features, as well as the accumulation of high C concentrations on nearly (001) planes.